Well Steve I agree with the assessments. It really does look as though it is just cosmetic damage, but I can also appreciate that fact that you both want to make things right.
Your detailed steps to fix the problem seem to be right in line with how it should be repaired, however......
Consider this: Based [only] on the pictures that you present, it really does appears to me anyway that this is not a major structural concern, hence the assessments made by 3 separate parties to that effect.
So, in the end you theoretically would be left with same situation. "having to answer about that corner and why it looks that way" whether you leave it as is or repair it.
I've been in a few homes over the years and every time [for us anyway] our concerns were always more about
- are the rooms big enough?
- will furniture we have fit?
- is the kitchen updated?
- are the windows to old?
- what are the major concerns with the house?
And if I was buying this home and the owner showed proof to me that 3 separate individuals....ALONG with my home inspector stated that this damage was not structural and the termites are gone...I wouldn't blink an eye.
But if you still feel strongly about repairing it, the way you have suggested is the way I would do it. And here's a tip:
Rent a multi-master