Go for it! It's a small thing and as long as you inform the readers it should be cool~
I don't mind it, but I recommend calling it out before every episode.
The comic In Blood Of Colour66 is a great example.
We all have a ton of comics in our reading list and often follow the stories over months and years. Nobody will remember how to read it if you mentioned it long time ago in episode one.
So go ahead, but make sure to be clear about it on every upload.
We don't read japanese or speak it nor is it translated from japanese so basically you're just shooting yourself in the foot. There's no reason to write it in that fashion. It drives people away from your work and frankly gives me aneurisms. This is akin to including kanji as sound effects and then translating it below for the english audience despite the comic being written entirely in english. It's annoying and pointless.
I don't find it annoying to read, I've read enough manga to be used to it--but I also don't think it should go right to left unless it was natively in a language that read that direction. That said, you can ignore our advice and keep doing you, it's not inherently bad and isn't going to impact you on Tapas. If you want to be published some day though, I would encourage you to go left to right on your next project. The industry won't take you seriously if you're paneling it backwards.
I know you want it to be authentic because it's what you know and what you love. But as a fellow author who is very inspired by manga, I need to tell you: You will never be an authentic mangaka in the way you want to be. You are not from Japan, and neither the Japanese nor the Americans will accept you as one (Even if you're not in the U.S., this applies). I have had friends who know I make a comic that could be considered american manga tell me to my face that they would never buy a manga with an author whose name didn't sound Japanese. You will get that bias from both manga fans and non-manga fans, which puts you at a disadvantage. It's why I always refer to my comic as a comic and not a manga, and why it reads left to right.
Ultimately the decision is up to you, but please think about it more if/when you get serious about selling it. It's something that needs a lot of consideration!
Eh, it depends on the comic. If you know how to properly format text to flow with the panels, it doesn't matter which way it's oriented - just so long as it's placed correctly and doesn't interfere with the art. I know Snipster's A Matter of Life and Death, which is one of the most popular comics right now (with like, 60k+ subs and growing) is read right to left and it does it quite well.
But most people who are make right to left comics (read: most, not all) do it because "MANGA DOES IT!!1!!" and so they aren't really properly trained in how to do it correctly.
No, it's not annoying- as others have said, just make it clear in your description that that is the way your comic is formatted and there won't be a problem. Tapastic is not a good site for this format sadly, as they (some staff) feel like it's "Confusing" ect. Plus, if you look at the recommended comics by Tapa, I have never once seen a right-to-left format in there. I'd like to be proven wrong on that though! 
However, if you want to make authentic manga, then as you say, right-to-left is the correct way to panel it to be closer to the original Japanese format- so go for it!
That's the joy of self-publishing, do what YOU love, and what YOU prefer, because at the end of the day, it's you that needs to be happy with the work. ^W^
There are still some of us that run right-to-left on the site, myself included, so join us lol. XD
I don't mind it too much as long as the flow of the word bubbles stay consistent and having a friendly reminder at each update would be helpful as well. It doesn't even have to be in-your-face, could just be a simple arrow at the top right corner of the page.
Short answer: No, it's not.
Longer answer: What matters the most to me is that the reading order of both panels and bubbles is clear. Whether it's from the right or from the left doesn't matter as long as I get a reminder at the top of each page (just an arrow is enough). As revisionstudios said though, if you intend to publish you should go with left-to-right.
well, you made it pretty clear that its right to left, which is a big butt-saver. and it does look pretty authentic, so im personally not thrown by the right to left-ness.
however, i dont know how much the rtl setup works outside of japanese-language comics regardless. i understand the authenticity motivation, but as others have mentioned it causes a clash with the text direction. also, youre making your comic for a western audience (youre posting on a western site, for mostly westerners, in english) - its easier to accept that, and that your webcomic is manga style as you stated, and not manga, than it is to alienate some of your audience and potentially cause yourself lettering problems.
manga is written right to left because of how japanese is written. this might sound harsh but, im more forgiving of translated manga, but if it's just like that for the aesthetic or to mirror translated manga then i usually get too bothered by it and dont care to read it. sorry :'v
I think you missed the part where I said "personally I don't like it" XD I'm just stating my own preferences. I'm fully aware that not everyone is like me.
There was Undying Happiness3!
I find that reading direction is never an issue after a person has adjusted themselves to it, and most people can do so fine (unless they're stubborn).
I personally believe that it's better to organise text to go from Top-to-Bottom as much as possible if you want easy clarity. I could probably even handle a comic that constantly shifted from right to left or left to right, as long as they are always Top-Down. (And similarly, I have trouble handling ones that mess with Top-Down orders, even if they are left-to-right.)
Celestial Wheel is the last right-to-left series we remember being featured by staff (Staff Pick?). That was May 2016. Since then the series has gone to left-to-right.
Shouldn't be a problem, most of us grew up with mangas. Consider it's a rarity in online reading, and you'll need to state it at every page. That might end up annoying
I actually prefer making and reading from left to right because of me growing up reading mostly manga (both in Japanese and Danish) when it comes to comics. The only western comic I read was W.I.T.C.H., so I'm way more used to reading comics right to left.
personally I don't mind it as long as it's clear which direction I'm supposed to read. But this could be just me, since I was never super good at telling my lefts from my rights.
But whatever reading direction you chose, make sure you know why you are choosing to do so.
A little, I need to be reminded all the time, not just in the beginning that I have to read from right to left because I follow a lot of comics and when they upload a new chapter I start questioning if I am reading it wrong when things are not making sense lol.
Once I remember it, that's ok.
It's not annoying per se but you also gotta remember that the only reason manga is read from right-to-left is cuz that's how it is in Japan and other countries. It's not a conscious choice in storytelling or art or w/e so I don't see the point in imitating that aspect. If it was possible to flip reading order without fucking up the art, localizations would do it. If you're looking to fool people into thinking yours is a translated manga from Japan, then yeah, sure. But if you just like the style and look of it, I'm generally against it. It's another matter if you're just so used to that reading direction that you think about your panel layouts the same way and it's hard to flip them in your head, maybe.
So, yeah! That's just my 2 cents. I'm used to reading in both directions so I don't really care as long as I have some way of immediately being able to tell which reading direction to go with.
