Awesome, where can i get the actual mods that work with this charsets and works with mayday or any other god tileset?
the arthor of these graphics already said that the custom civilizations need to me made personally. as for the mayday i'd suggest making a new GRAPHICS_<name>.txt file then copy from the .txt files from here and paste to the new file. copy mayday's first then use that one as like a template of place holder but be careful if you want to use both i'd had to edit (picture based copy pasting through an image edit tool) to not have any overwriting or keep which ones i wanted to use.
example:

graphics_all
[OBJECT:GRAPHICS]
[TILE_PAGE:DORFS]
[FILE:mayday/dorfsMAYDAY.png]
[TILE_DIM:16:16]
[PAGE_DIM:12:27]
[CREATURE_GRAPHICS:DWARF]
[TRADER:DORFS:3:1:AS_IS:DEFAULT]
[TRAPPER:DORFS:5:21:AS_IS:DEFAULT]
[DEFAULT:DORFS:0:0:ADD_COLOR]
[STANDARD:DORFS:1:0:AS_IS:DEFAULT]
[CHILD:DORFS:2:0:AS_IS:DEFAULT]
[BABY:DORFS:3:0:AS_IS:DEFAULT]
[DRUNK:DORFS:4:0:AS_IS:DEFAULT]
[MERCHANT:DORFS:5:0:AS_IS:DEFAULT]
[DEFAULT:DORFS:10:0:AS_IS:ZOMBIE]
[DEFAULT:DORFS:11:0:AS_IS:SKELETON]
[STANDARD:DORFS:10:0:AS_IS:ZOMBIE]
[STANDARD:DORFS:11:0:AS_IS:SKELETON]
[TILE_PAGE:KOBOLDS]
[FILE:civ-chariot/kobolds.png]
[TILE_DIM:16:16]
[PAGE_DIM:12:22]
[CREATURE_GRAPHICS:KOBOLD]
[DEFAULT:KOBOLDS:0:0:AS_IS:DEFAULT]
[STANDARD:KOBOLDS:1:0:AS_IS:DEFAULT]
[BABY:KOBOLDS:2:0:AS_IS:DEFAULT]
[CHILD:KOBOLDS:3:0:AS_IS:DEFAULT]
[DRUNK:KOBOLDS:4:0:AS_IS:DEFAULT]
[CHAMPION:KOBOLDS:5:0:AS_IS:DEFAULT]
[THIEF:KOBOLDS:6:0:AS_IS:DEFAULT]
[MASTER_THIEF:KOBOLDS:7:0:AS_IS:DEFAULT]
[MINER:KOBOLDS:0:1:AS_IS:DEFAULT]image is example if image based copy-paste mixing the two. both actually used same reference so i just "kept" chariot's image file and replaced (covered up if referring to the edit process) the thief classes with mayday's.
the code text is example of using a bigger single file then linking proper image and directories. key point is where it says [FILE: <location> ] then everything will be good.
of course always backup but in the case of the text files, just move them out of the raw/graphics folder while keeping the new single .txt file.