Not blaming you
It's the original sprites from the game...
And conercining the memory rooms: Those aren't moving at all so there won't be much of an issue.
(And these are not many at all..
)
It could get problematic when you make something like a big town map with lots of moving sprites.
Nothing more than a reminder..
Recreating existing ones would take a lot of time, which could be used in a better way.
Since the performance isn't at stake right now I'd rather stick to making new ones...
Oh.. and watch out for the mighty mouse.. It hates fanart... especially of the pornografic type...