Eurkey as default and toggle among different layouts?

[zenny]

Hi,

I switch between ultkeys (that supports all latin-based European languages with different glyphs, see https://github.com/pieter-degroote/UltimateKEYS), Greek (gr) layout for mathematical notations, Pali-Sanskrit (pi) for oriental inscription ( https://github.com/bdhrs/pali-sanksrit-keyboard-for-linux) and Arabic (ar) for Arabic layout, and toggle between them by pressing Ctrl_R and Shift_R in a 104-key US keyboard by running:

setxkbmap -layout ultkeys,gr,pi,ar -option grp:rctrl_rshift_toggle,caps:ctrl_modifier

But this has become an issue after I tried to move to kanata by making changes to the US layout with layer aliases (mostly inspired by @jtroo's config), but could not figure out how to configure ultkeys as default input, and maintain toggling mechanism between the Latin ultkeys instead of us layout and other layouts?

Any inputs apprecated. Cheers,
/zenny