Think of nesting as a wrapper, if there’s something going on with the clip that is rendering oddly, nesting it can act as a nice, sanitary little bubble to prevent any interaction between plugins or parameter changes.
The text is just a sequence/clip on a track, it shouldn’t matter what you are inserting, it should just insert. In Mocha, the surface tool is linked to the track by default, the surface tool is also the visual representation of the track. When you’re doing an insert, the surface tool is where the insert populates whether you are inserting text or a screen or whatever it is you need to insert, and whether or not that is an insert layer or an outside PNG you are importing into Mocha. There’s no need to link to any other track, as long as you’re using the surface tool on the layer you tracked for your insert.
Think of it like sticking a sticker over something. The surface tool is the border of the sticker.
If you have a number I can reach you at, you can email it to email@example.com and I can call you, it might be faster than going back and forth here.