This probably relates to MVDSV settings more than this mod. The best part about coop mode is that team play can be utilized when playing maps from the following list and even support high resolution maps/entities/textures, if MVDSV would support it. I think it's a matter of updating the max entities and max map size in MVDSV. https://www.quaddicted.com/reviews/?filtered=huge
This map works https://www.quaddicted.com/reviews/moonlite.html
This map does not, though it loads and subsequently crashes https://www.quaddicted.com/reviews/gmsp3tw.html
These maps probably wont work: https://www.quaddicted.com/reviews/mapjam6.html (maps/jam6_daz.bsp 15Mb)