The combination of Ars Énergistique and Applied Flux should make it possible to power everything with source either directly or through conversion (whether or not it’s practical remains to be seen). I’m currently on a version from before create was updated and won’t be updating the pack unless Ars Creo is compatible as well.
I haven’t tried those mods but hopefully they buff the conversion rates. Historically, magic to RF has been a terrible deal in my experience.
In my own world I got around this by using cross-mod shenanigans to dupe diamonds, then burned the diamonds for fuel. That seemed sufficiently magical for my headcanon