My understanding is that if you change the contents of a torrent you’d have to create a new torrent to seed the result. You can’t change the contents of a torrent and expect other people to receive the modified files via the original torrent. Your client will be doing a checksum and realizing its local files are corrupt (due to your changes) so replacing them with good copies.
So create a new torrent with the modified files and an explanatory title, and seed that.