I believe there's a simple solution for such problem, obviously not the best, but please implement it because we really need it.
Add a external copy button, such will create a json structure of the elements, a very bad example (bad json I know):
this structure will represent a webflow object, of course, then there's the issue of class crashing... but the solution is simple, since this structure is analyzable, you can know whether when doing an external paste from the clipboard, if there are going to be issues of such sort, in which case, you'd ask to rename the class or add a prefix to all classes if there's a lot of issues regarding crashes. The same applies for ids.
The buttons external copy/paste seem (to me) rather simple to implement, and the best is that you would be able to regenerate the whole content of a website by external copying the whole body, simple.