Many bug reports are not acted upon immediately. No one is accountable for addressing bugs. However, that does not mean someone some day in the next year or so will not look into this forum category for bugs to work on.
I could not reproduce most of what you are describing in v17.11. You might have been affected by this bug that was fixed in that version:
Also, multiple times you wrote “split the first clip and applied a text filter to it” without explaining exactly which half “it” is. When you split a clip there are now 2 clips that are distinct and can have separate filters. I chose the second half that would be involved in the transition.
However, you are correct in noticing that there is a difference in behavior between applying filters before or after making a transition.
Actually, I believe most people expect the filters applied to a clip involved in a transition should also be applied during the transition, and that is the direction I am going in to address this bug - the opposite of what you said above.
Then I added the same two clips to another timeline. Moved the play-head to the beginning of the timeline then moved it ahead 3 secs. and split clip one. Then applied the same filters to the first part of clip one.
Next I added the transition between clip one and two.
Now when I play the entire sequence the filters applied to the first section of clip one do not show up in the transition. This is the video.