Yumetso comes from this two combination of words, "Yume" and "Tso". "Yume" means dream, and "Tso" means on. So basically this gender means "dream on"(Like that song)
Pronouns ideas: Yumetso/Yumetsos/Yumetsoself
Yume/Yumes/Yumeself
Tso/Tsos/Tsoself
Tsu/Tsus/Tsuself
Thats basically all I can think of