I just want to add to this interesting discussion that in Indonesian keris society the typical 'raksasa' Cirebon hilt were called 'buta bajang' which means dwarf giant(?)/
raksasa. But as Alan mention somewhere on the other thread, they might represent several characters (I think Jagal Abilawa/Bilawa/Bima, Rajamala, dwarapala-at least his posture as a guard- etc) to which I'm agree.
Specific to Semar/Smara/Smarasanta he is an avatar of Sanghyang (God) Ismaya, other punakawan Bagong is (made of) his shadow. Semar is like yin-yang symbol in Chinese philosophy, or kain poleng (checkered cloth in Bali) not good looking but is wise/powerful (God), a male but has breast, old looking but has a child hairdo, sad eyes but always smiling etc. Gareng & petruk got their appearance from a fight between them (previously good looking). I don't know how old these character is started to be used as keris hilt, but I don't think it is 'traditional'/very old practice.