After seeing MarphitimusBlackimus's Video about the unreleased cloister.bsp by Marc Laidlaw I decided to the necessary fixes. The only leftover of this map was an untextured .map file with lightning and a teleporter.
I took myself two evenings back in the day trying to bring this close to Mark Laidlaws description of the original map. I basically textured the map, added playerspawns and weapons, fixed the broken brushwork (mainly at the pillars), changed the lightning and made a few small changes.
The original fixed version was released on 15.04.2017. On 02.01.2018 I fixed some critical brushwork, where you could get stuck previously [only in my version ;) ]
If you look for a graphically and design-wise more advanced version of cloister, watch out for dm_lister. dm_cloister17 should have better weapon and spawn balance though and it's absolutely easier to install ;) [only the .bsp file, textures are included].