While my experience is not heavily related to Tapas, I can definitely answer this 
I'm from the United States, all the way in Chicago Illinois, and I've done several collaborations with a young woman from Brazil. She's also an aspiring artist, and her skills are amazing. Most of the collaborations we've done have been more art-based than comic-based, and it was more conceptual art for stories we planned together.
I will say that before we got to this level, we first met as writing buddies, taking turns adding parts as we went. Then, we got to learn more about each other, what we love about drawing, and our day to day lives.
I've touched on this type of topic before here: Building Connections. Whether your partner is in the same country as you or in a different country, I still think this topic would definitely help you with the nature of trust in a collaboration.
The bottle line is that your collaboration is as trusting as you make it. You have to sorta get to know someone if you're going to be doing a big project together. It helps knowing who you work together with in order to vision what you're working on.
I hope this helps a bit! 