Wait, now that I think about it... It probably uses "" for some parsing. For example bold text is **text**, so whatever it is, it probably uses ""text"". I use the "" appearance twice I think, so it probably messes up any additional formatting in between those. That's kinda annoying.
Edit: I played around with it a bit.
https://wiki.frictionalgames.com/playground/playground
As you can see, quotes are parsed as _fckg_QUOT and fckg_QUOT_. Perhaps the real method of getting past this is to use the <nowiki> tag I've seen a few times, but I decided to just go with
If empty instead of
If "". It seems to have fixed it for now, but any further edit to that page will corrupt it again. It's not when it's first written that the issue occurs, but when it tries reparsing it later for the editor again. So opening the editor and saving is when it happens. The only way I see to get to the editor and bypassing this is to use the Basic DokuWiki editor (DW Edit button) but when you click that, it saves the work right before, so you corrupt the page in the process.