You can add the much hated "translating from a translation" to that list, along with not using the proper font, not cleaning, imprecise typesetting, etc. All the stuff that semi-pro scanlators complain about, but that most readers don't actually notice.
Sometimes even the "pro" for pay manga make these kinds of mistakes (including damn nigh near machine-translated dialogue) and people still pay $2 to $5 a month. I remember seeing tiny text that wasn't properly centered or spaced in Manga Plus recently, and non-cleaned sound effects with just a description on what the SFX says on the side in both Shounen Jump and Vizmanga (although they might have fixed it by this point) and recently, clunky dialogue that seems machine translated is popping up here and there on simulpubs.
And yes, I'm talking about from the official manga publisher with either ad supported or pay to read manga. With the caveat that it's usually this way on first release, and then they go back and replace the rough stuff with the proper translations when they're about to release the physical volumes or sometime before then.