Ok, then I’ll do that, any idea which is the best component, platform, e4, etc. in Bugzilla?
Platform UI is the best candidate.
We should actually consider dropping the e4 component and the e4 mailing-list to replace them by regular platform stuff. I'll open a separate thread about that.
is there a Chance such a bug might be fixed for Eclipse 2020-06 (4.16) as well or only the newest versions?
The Eclipse project welcomes backported patches to older branches as long as committers agree with it; but won't build nor ship binaries based on an older branch. So even if a patch gets in the 4.16 branch, you'll need to rebuild the bundles you want to use in it and ship them in your product. Note that those "forked" bundles would probably not be welcome in SimRel.