Good question ^^. I had same problem, and it take lot of time to rename all screenshoot, I prefer keep the same rom name and change snap name. The rom need to have exactly the same name than the snaps.
3 easy solutions I m using.
CKRename, you can use it to remove some character like Tags or years in all the folder in 1 click.
EmuMovies Download Service Utility, this one can download snaps and rename them exactly like the rom name.
Download special snaps pack made with rom name from database like tosec or nointro.
Some rom manager have option to rename rom without tag (never used them, I can't help you with that)
More complicated, you can use script, or special application made by other people with same problem, I have already see some of them but I haven't memorised their link ....
But noone of them are 100/100 effective, I spent lot of time to complete my snaps pack, with a script that search on google image, suggest a snap and waiting for a validation from me.
Just for information Amstrad have more than 8 000 rom and no complete pack (with the good name), you can imagine the work. I can understand your distress ^^.