who made the 25th anniv. DotM episode pls? solely J.F. Gustafsson's work (the DoPa creator)? 

Dimension of the Machine was made by several people from MachineGames:

Christian Grawert
Andrew Yoder
Tom Fritzson
Kevin Dunlop
Oscar Göthberg
Kristoffer Kindh
Erik Hörnström
Anton Eriksson
Iuliu-Cosmin Oniscu
Abigail Cox
Dennis Karlsson
Sabina Sveica
Pierre Willbo
Jens Matthies
Jerk Gustafsson 

got some FPS drops w/ Enhanced engine, which older engine can run the DotM episode5 platforms correctly pls? tried copying MG1 directory from Enhanced Quake to a directory of my Quake game with some older egine and running it like this

quakespasm-spiked-win64 -game mg1 +r_farclip 100000 +sv_protocol 999 +sv_aim 1 +scr_conscale 2 +gl_flashblend 1 +scr_crosshairscale 2 +scr_menuscale 2 +scr_sbarscale 2 +scr_conwidth 1920 +sv_aim 1 +r_maxsurfs 4000 +r_maxedges 16000 +skill 1

to play new DotM maps. the 1st four miniepisodes and boss fight work, some broken platforms in episode 5 tho (had to use noclip cheat in mge5m1+mge5m2 maps) 

Most of them should put to autoexec.
r_farclip
r_maxsurfs
not needed, use default
sv_protocol 999 QSS used by default,
scr_conwidth 1920 - why so much? - try default
gl_flashblend 1 - try 0 {not affected to performance on my machine}
What is in Your autoexec? Your hardware specs? 

a ryzen and GTX980 Ti. how about DotM jam any time soon pls? the new textures are awesome 

No one needs permission to call a jam at least not here. 

ok, so is there somebody here able to extract the textures from the MG1/pak0.pak file pls? I assume TrenchBroom can do DoMa-style rotating brushes/cogs/fans? 

There has been a jam using textures from the remaster. sm_217. 

Of vanilla bugs which have NOT been fixed in the re-release? Speaking of code-related issues like the fish count bug or Megahealth rot issue, not map-specific stuff like incorrect spawns. 

The remaster has a number of classic bugs in the gamecode, while also introducing a few new ones in the engine. But as it is I don't care about fixing bugs in the remaster's gamecode, because if the fixes aren't released in an official update, they won't be compatible with achievements and such.

If there was any hope for another official update addressing community feedback, sure, I'd do a lot of research to help. I don't care about fixing my experience, but I would certainly value being able to provide bugfixes to improve everyone else's experience.

The whole point of the remaster was to give an updated experience for everyone who bought a (digital) copy of Quake. If we have to go back to unnoficial fixes to use it, I prefer to simply stick with the classic community-made engines and mods we have with over two decades of improvements. 

Ever encounter this issue here in SoA?

I dunno if it's port-specific, but at least in Ironwail, the exit of HIP2M4 doesn't look the way it should. 

https://github.com/andrei-drexler/ironwail/issues/230 

https://quaketastic.com/files/screen_shots/hipdm1.jpg
https://quaketastic.com/files/screen_shots/hip2m4_1.jpg
https://quaketastic.com/files/screen_shots/hip2m4_2.jpg 

that door texture on hipdm1 is not a bug, it's the same in the original 

That map is missing a couple of textures in its BSP file compared to the original, especially "black", "names", "wexit01", "exit02_3", "+0butn" and "wizwood1_3".

However, even if you copy those over manually from the same map in the original release, the exit isn't textured properly, misalignments all over the place.