Currently, if a mod were to support both Forge and Fabric, it requires uploading two separate entries for the version, and hoping that the users download the right one.
On top of this, only the last uploaded will appear on the recent releases sidebar, further harming the ability to download the right version.
My proposal is to allow a single "Version" to contain multiple jar files that target the different platforms. There's already a way to upload additional files, but extending this to actually allow specifying them as different platforms in a way that the website supports would majorly improve both the mod author workflow, and the user discovery process. In the past, the Twitch Launcher also had issues installing mods that existed for both platforms. This would hopefully alleviate any similar issues with either the Overwolf Client or third party clients.
It's also possible to have a single jar for both mods, so being able to just select the platform via a checkbox rather than a dropdown would allow a quick workaround. IMO doing this is ideal anyway.