A good question!
Kaleidocrystals are fundamentally multiversal energy weaved into a solid form. That means depending on how refined the form and who is touching it, its power output varies.
Refined by Ampla and in the hands of someone experience with converting that energy into something useful like Iona? Then its a very versatile and strong power.
An unrefined version of a creation of someone with nefarious intent like the one from Blood & Sand? Very powerful but incredibly unstable. Its a lot of power without any control.
If its refined well and in the hands of a non-variant, its practically just a nice shiny crystal. Probably prime tat to be sold in those witchy shops. Practically powerless.
So fundamentally they're very powerful when it comes to raw energy.
A variant is always going to get more power of it than anyone else due to it being energy fundamentally tuned to them.
You can power an entire complex, you can use it as ammunition or use it as a teleportation device.
Part of their strength is their versatility and attunement to variants.