I've never had interaction from Tapas, but I have had quite a bit of interaction from Webtoon Canvas. (That said, I only really tag Canvas now - you kinda have to choose, as both platforms will be less likely to signal boost you if their competition is also tagged.) It's mostly been on Twitter, as that's my main platform. They've retweeted me a bunch of times, and I've been featured twice on Webtoon, which I believe initially stemmed from the fact I made myself visible to them on social media.
They've retweeted my comic update posts a few times, and they also retweeted a compilation of my favourite Canvas Hidden Gems during the Canvas Festival, which wound up netting me a few followers. (And hopefully a bunch of subs for the series I put there!) Generally, social media attention doesn't result in a meaningful sub boost for me, but it's nice to know the Canvas staff know about my comic.
On Instagram, I've never had my posts shared by either Canvas or Tapastry, but Canvas often respond to comments. Beyond that, I can't vouch for how much a story share or something on Instagram would affect followers or subs.
But yeah, it's well worth tagging Canvas and Tapastry! Social media activity itself may not do much, but if the staff teams see your comic often, you're more likely to be earmarked for features, and those are huge.
