A long while back, when I was first starting to get confident about asking questions on this site, I had a question I wanted to ask. However, I searched, and the question I wanted to ask already existed for quite some time, but it was [closed] because the querent had not specified the system even though it was very obvious it was D&D 5e.
I was a bit at a loss for what to do. Normally, one would just edit the question to fix the issues with it so it could be reopened. However, I was also aware of RPG SE's "don't guess the system" policy, which meant that it's not such a simple matter of adding the [dnd-5e] tag. I considered re-asking the question, just with the proper system tag. However, then I'd be asking a duplicate question, which usually end up getting closed.
I finally considered bringing up this issue on the meta, but as I was an inexperienced and new user, I did not feel confident to do so at the time, so I ended up moving on and leaving the question behind. However, today is a different story. Although the original question has been both lost to time and memory, I still believe this is an issue enough that would warrant some discussion.
So, because I did not ask then, I ask now: what's the proper way to handle this sort of thing?