Is the issue surfacing for end-users who have Mylyn installed but not used? Is it blocking further usage or just making Mylyn feature fail? Is the failure hard and ugly or is it some error pop-up, or an error view or a log entry when trying to use a bugged feature...?
I think if it's only affecting Mylyn, not cascading to other workflows/components and only on Java 11, the amount of users who're using Java 11 and Mylyn simultaneously should be low enough to make it acceptable to ship it as it anyway without respinning or delaying anything.
And if we need to respin something, we could consider just removing Mylyn from EPP packages instead of rebuilding the whole SimRel.