for gtk2 apps suchy as Epiphany you can use im-ja:
http://im-ja.sourceforge.net/
you'll need either canna or freewnn conversion server installed.
instead of installing the RPM, try extracting the font file(rpms can be opened and extracted by midnight commander) then install it manually, to $HOME/.fonts
If you have another windows machine/installation try using MS Gothic, imo its the best looking J font.