If I delete one of my own uploads (due to artist error), will I be penalized for those deletions if done within 48 hours?

Yes, your deleted posts count against your upload limit. But that's it, and it only counts in that every 4 deleted posts will subtract one post from your upload limit. And even if the upload limit reaches 0, you can ask an admin for it to be bumped back up...

So really, while it does effect something, it doesn't have much of an effect. The only "penalty" the 48h deletion is that it causes a post you uploaded to be deleted, and the penalty for deleted posts are as explained.

Alright, thank you

There's also the penalty of making other users upset, especially if you use that reason when another reason would suffice (Artist requested removal is fine, "Corrected version coming soon" not so much)

To clarify, this is no "official" penalty, just people's opinions