I had exactly the same problem. I ended up getting a copy of its source and pointing Claude at it, which insisted there were bugs - but, its fixes were not reliable, and I wasn't even sure if its assessments were correct, or the docs were wrong or out of date, or I was simply misusing it and misleading the AI through those expectations.

The docs point so strongly at using v2 instead of v1, but I just don't get the sense it's reliable, and I feel 'stuck' for a good Terminal UI library for .Net now.

I don't think there is a perfect fit, unfortunately. The best one can do is probably call out to one of the native code libraries, but that has an impractical distribution story in .Net for many use cases.