Mind that the three cavern layer grasses mix in your fort, so best use sprites that work well next to each other.
I have done so. and I am just done wrestling with the overrides. The following works fine:
[OVERRIDE:46:T:GrassLightFloor1:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:44:T:GrassLightFloor2:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:96:T:GrassLightFloor3:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:39:T:GrassLightFloor4:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:46:T:GrassDarkFloor1:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:44:T:GrassDarkFloor2:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:96:T:GrassDarkFloor3:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:39:T:GrassDarkFloor4:4:R:8:135:136:151:152:167:168:183:184::::FLOOR FUNGI:]
[OVERRIDE:46:T:GrassLightFloor1:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:44:T:GrassLightFloor2:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:96:T:GrassLightFloor3:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:39:T:GrassLightFloor4:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:46:T:GrassDarkFloor1:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:44:T:GrassDarkFloor2:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:96:T:GrassDarkFloor3:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
[OVERRIDE:39:T:GrassDarkFloor4:4:R:8:133:134:149:150:165:166:181:182::::CAVE MOSS:]
// below are Null overrides, the above won't work without them for some reason.
[OVERRIDE:46:T:GrassLightFloor1:0:46]
[OVERRIDE:44:T:GrassLightFloor2:0:44]
[OVERRIDE:96:T:GrassLightFloor3:0:96]
[OVERRIDE:39:T:GrassLightFloor4:0:39]
[OVERRIDE:46:T:GrassDarkFloor1:0:46]
[OVERRIDE:44:T:GrassDarkFloor2:0:44]
[OVERRIDE:96:T:GrassDarkFloor3:0:96]
[OVERRIDE:39:T:GrassDarkFloor4:0:39]
Updated screen.