I don't know if it's even possible, because I'm not even gonna pretend to even remotely understand the simplest of codes in java.
But, something that would be awesome would be that the addon it-self scans what version of forge you're using and uses that version of Replay Mod.
Alternatively a downloader within the game it-self, where it says: "Download Replay Mod", and that in turn downloads the right version, tells you to restart the game, you restart the game and you have the right version ready to go and the downloader disables it-self if these conditions are met: "Condition 1. The latest version of the Replay Mod is installed" and "Condition 2. the Replay Mod version doesn't match the game version", if they're not met, it disables all versions of the Replay Mod except the downloader addon, and then again tells you to download the correct version and then restart the game when it's downloaded.
Again, I have absolutely no idea if it's even possible, but it makes it easier for us to get the right one, if it isn't at all possible, you can just ignore and/or delete this post.
While that would technically be possible I don't think it should be done for several reasons:
1. No other mod (I know of) does that. At the moment the ReplayMod installs just like every other forge mod (ignoring ffmpeg). Changing that might confuse people who just barely know enough to install forge mods and irritate those that are pretty familiar with modding.
2. While it would be technically possible, it will be ugly both to implement and to use
Above two points are less valid if the updater addon is optional. This last one however isn't:
3. It's quite a lot of code which would have to be written to automate what I would consider a rather trivial task. I assume you had this idea because you switched up the 1.12 and 1.12.1 version. Note that this is actually a bug (will be fixed with next version) and the 1.12 version shouldn't even load on 1.12.1 (and vice versa) but instead outright tell you that its incompatible (see screenshot). So once this bug is fixed, using an incorrect version will be less of a pitfall than it was for you.