The server library for Linux (dlls/spirit.so) is the original Spirit of Half-Life 1.2 code implemented into the hlsdk 2.3 (with a few changes in order to make it work...). The client (cl_dlls/client.so) is build from unchanged hlsdk-master code as I was unable to make the client library work properly with the spirit code (or more precisely - unwilling to sort through that undocumented trash).
Initially I wanted to release the Linux libs separately to be used in order to make any SoHL 1.2 based mod work on Linux. But since I did make some changes and I didn't build the client library with the spirit code at all, I'm not sure about how compatible the libs will be with other mods (though I think most Singleplayer mods based on spirit 1.2 should work fine with these libs). I did play through Blbej Den on Linux without an issue (though Blbej Den is only taking advantage of a few of the spirit features...)
Feel free to test the Linux libs with other SoHL 1.2 based mods (just modify their liblist.gam and copy over the dlls/spirit.so and cl_dlls/client.so), you may also reupload the libs separately from this mod wherever you want... I just didn't want to do it as I'm not sure about compatibility with other mods and I don't have the time to test it with them.
Btw, Blbej Den looks better on Linux as the Linux libs are taking advantage of SDL2.