I think I may have bought a frankenwatch?

It will be good if you can return it and I sincerely hope it works out. No harm in opening a claim with eBay and see what they think. It may depend on the details of the listing, since overall I'd say that the watch is still authentic, just with a refinished dial and perhaps replacement hands, both of which happen regularly with old watches and are very common. The majority of vintage watches sold on various platforms have issues like this and unless the listing specifically says that the watch is all-original, it may not be considered fraudulent.

Obviously I feel that sellers should be honest and transparent, and saying that a watch is "restored" or "refurbished" is a bit sneaky, since newbies don't always know what that means. However, many sellers may not even know the history, and these details can be pretty subtle. If a seller has a number of watches listed, I often look closely at all of them so that I can get a sense of the type of things he sells. Many sellers have a pattern. Some pick estate sales and flip things immediately. Others restore watches. It can be helpful to get some context if possible. Also, it's helpful to get a sense of different watch "cultures" around the world. In some places, it is particularly common to re-paint dials.

This is a tax evasion, just don't do it - any blowback or customs fines will fall on you. Follow the eBay returns steps, as discussed in your other thread.

You’re financially out of pocket, so in your position I’d get what I could out of it.

Pleased to hear you’ve been reimbursed by eBay. Kudos to them.
My suggestion is that, just in case, you leave it in a drawer for the time being.