Bugs: 3.5 was *remarkably* stable considering it's a community-driven project. However, given the number of players CB has, and the number of hours each of those players put into it, we did encounter a handful of weird engine bugs relating to audio & thread-safety.
Regarding publishers, none of the ones we pitched CB to (in 2019/2020) seemed to be put off by our decision to use Godot. If they were, they didn't say it. And actually, a few were quite interested in Godot themselves even back then.
Godot is perfect for small projects. For medium/large indie projects, if you're not afraid to get your hands dirty with C++ engine code, 3.x is already good enough! I suspect that Godot 4.x will be in a similar state next year, and continue to improve after that.