Different cases require different actions — there’s no single answer for every question.
The TC issue, the font issue, and the last example are three completely different situations. I already explained how to handle each of them separately.
Why you keep trying to apply the same solution to different problems — I honestly don’t understand.
I suggest you read about non-manifold bodies — maybe that will help you understand things a bit better. These kinds of bodies are not allowed in Shapr3D.
Agree, I was trying to describe 3 different approaches for 3 different problems and tested them.
2. The control dot.
This is where your problem is: control point inspection only works for spline-related issues. But for some reason, you’re trying to apply it to problems that have nothing to do with splines.
You could also just click on the bottom face, then go to Extrude, so you don’t need the sketch. Makes your viewport an history simpler. Just make sure your extrude doesn’t go to Union mode automatically.