----- Original Message -----
If we absolutely need to have a solution that derives a default input source from the display language (which you still have to set up initially, anyway), I would suggest to do it inside the settings-daemon plugin, and only if we detect a 'pristine' system, ie no input sources configured at all.
We already do that, kind of, as we use the XKB configuration from the X server to set the default input-sources.
I don't understand how this would have worked in the past. Would you have applied just the iBus configuration, just the XKB configuration, both? Where's the list of language to input sources matches?
Anaconda could also drop the default layouts in a GSettings overlay, and we wouldn't have to do anything special.