Here is something REALLY minor, but I thought I'd bring it up nevertheless, for cosmetic's sake.
The par times for TNT and Plutiona are the same which were originally calculated for the regular Doom 2 levels. This was already the case in vanilla TNT and Plutonia and never made any sense. So I think these times should be removed from TNT's and Plutonia's map definition files in ZDoom.
On the other hand, for Chex Quest 1 where the ZDoom definition file copied the par times from Doom's E1M1-E1M5, there DO exist valid par times - the official Chex Quest 3 release which also included episodes 1 and 2 has these for episode 1.
So the times in the Chex Quest definition file could be changed to the following:
E1M1 - par 110
E1M2 - par 180
E1M3 - par 200
E1M4 - par 240
E1M5 - par 300