It's actually pretty easy to transform a snes/pce ips header hack into no-header with https://github.com/heuripedes/ipsbehead
(or just use bps).
As for wrong md5sum indicated on the romhacking pages, that's sadly not unusual because submitters often instead of checking with a md5, crc32 or sha1 utility they search for 'romname crc32' on google... which might get wrong results. We'll see what's happening here, but as a rule the readme has priority over the romhacking page checksum information for me.
Another common error is to only post the md5sum of the game *after* patching, which doesn't match the rom naturally.