Anything’s possible if someone volunteers to do it. You can file an issue but filing an issue is not a guarantee that the code will be modified. See How to file an Issue.
In the mean time, you can forego the automatic discovery and use Generic MQTT Things. It’s more work but you have full control over all aspects of the subscription and publication to the topics. Frankly, that’ll be a lot less work in the long run. It sounds like you only have a few relatively simple devices.
You’ll need to set up a dev environment (see Build System | openHAB). Once built you can put the add-on’s jar file into the addons folder for OH (location depends on how OH is installed).