I don't think it's possible to do what you want in the way you describe.
There is a function
https://mohoscripting.com/methods/scrip ... serttext-2 that will allow you to create text on a text layer or allow you to add text to a vector layer.
But the text and its attributes in a text layer are not animatable. Similarly, having created shape(s) on a vector layer, the attributes in the parameter block have done their job - but this does give you shapes that you can animate.
So (e.g.) if you wanted to change the colour of a word at some point in the timeline, you'd need to animate the colour of the relevant Shape(s) that had been previously created - e.g. animated fills / gradients / ....
Similarly, changing a font would mean creating two versions of the text then switching between them in some way -- e.g. using a switch layer; or animating layer opacity; or masking to reveal / hide...
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Speaking personally, I very rarely use Moho text -- Most of the time I create text in an external program and that text goes directly into a compositor as pngs or png sequences as appropriate where I can scale / position / ... or play with its colours ... / apply transitions ...
Sometimes, I might import png into Moho if I want the sort of (bitmap) animation that moho offers better than the compositor (e.g. warping using mesh / bones...).