"I guess that Rebuild could try to do something like remove little sharp segments like that which are smaller than the rebuild tolerance."

That would be awesome
Even better, one tolerance for the rebuild
+ One tolerance for the weld

It would obviously do the weld before the rebuild

Anyway, thanks for your answer and for being the only 3D software developer I know who directly reply to his customers so fast (I always have a big smile when I get answer on this forum in a matter of hours or minutes and not days !)