It seems to look ok.
There is no right way to decompile, it just works or not. If you feel that you lost too much quality, try to avoid decompiling at all.
As nUllSkillZ said, there are ways to change a texture in a map without actually touching the BSP. Scripting allows to “remap” about 14 shaders (safety limit) with another one, so you could “remap” specific areas of the map.
Look for special places in the map where the mapper used a unique texture. If you then look to the shadername in your decompiled map, you can “remap” that shader using the “remapshader” command in an ETPro script. Then you only need to package your new textures, and ask an admin to install the script.