Weird, that fixed it. I assumed that since the URL was exactly the same whether I ran it with ./nodebb start or ./nodebb dev, it couldn't be related to cache. I suppose I just don't know enough about how caches work.
I will edit the plugins locally then until the plugins's authors put the modification. Thank you @julian for this quick fix. @a_5mith could you let us know when you have pushed it to npm or github please?