you can´t remove PLi-HD skin because it is the fallback skin, if there is an error in other skins you ´ll get boot loop cause there is no fallback skin to return to, you can remove (manually) PLi_HD1, PLi-HD2, PLi-FullHD, PLi-nightFullHD, sikn_default? I didn´t rty it
about unused laungages, I ´ve seen this on OpenTAV
installing
opkg install enigma2-locale-{ar,bg,ca,cs,da,el,en-gb,es,et,fa,fi,fr,fy,he,hk,hr,hu,is,it,ku,lt,lv,nb,nl,no,pl,pt,pt-br,ro,ru,sk,sl,sr,sv,th,tr,uk,zh}
removing
opkg --force-depends remove enigma2-locale-{ar,bg,ca,cs,da,el,en-gb,es,et,fa,fi,fr,fy,he,hk,hr,hu,is,it,ku,lt,lv,nb,nl,no,pl,pt,pt-br,ro,ru,sk,sl,sr,sv,th,tr,uk,zh}