DosBox performance issues

DOSBOX SVN seems to be more stable for games like Rise of The Triad or SW Dark Forces but I can’t compile it. I always get errors. Also, there is a dosbox_svn_libretro.so but I can’t reconfigure the mapping and it does not seems to use the RetroArch mapping at all.

Is there a way to force a .so core to use the mapping from another source?
ex.I have mapping for dosbox-sdl2 and I want the dosbox_svn_libretro.so to use it

Or does someone still have the working version of dosbox_svn_libretro.so referenced in the post below: