"All I did then was manually install sourcemod-1.6.0-hg3897 to get my SM admin pannel back to normal as it was corrupted with weird characters... All seems ok to me so far.."
This was for a CS:Source server but i suspect you can use the same fix.. I recommend just reinstalling manually SM 1.5 see if that dose it for you first..
"SM does not use Valve's filesystem to see the maps dir in every search path. The code that checks that maps are valid only has basic filesystem functionality and only checks the immediate maps directory under the game directory. You can either move your maps back to <gamedir>/maps or
file a bug and someone may look into it if time permits."
All i did was move the custom maps to the new /cstrike/maps directory from /cstrike/custom/old_custom_files/maps directory and the maps show up in the list on your admin panel. I had to manually move the materials, models, sounds ect as well...
This was discussed here
https://forums.alliedmods.net/showthread.php?t=213697 already