The experience solidifier requires solidified experience to craft, which is unobtainable if solidified experience drops from mobs are disabled.

It would be nice if there was another way to obtain solidified experience, or perhaps use a substitute in the solidifier's recipe (vanilla enchanting bottles for example).

For alternate recipes, ask the pack developer. Or use something like CraftTweaker to do it yourself :)

I believe if the solid xp can be disabled via configs then there should be an alternate way in the mod

This is better left to an external recipe editing mod.