I see we're both working diligently today.
If it were me, I would border each letter block with the smallest smidgen (1/4"-1/2" ) of black or dark brown or dark cranberry. A color that appears in the blocks but way way deeper and darker. Just a smidgen. I like the cranberry.
I usually have at least 30 fabrics in my quilts. But I get that's not for everyone.
Those 3 samples are all so very close in value to the fairy blocks. So if you just surround ALL of the blocks with the SAME fabric...it's kind of flat.
The dark little border will help highlight them, and then you can see if you want to use multiple fabrics to border the blocks.
That won't make it too busy, since you'd want to stay in the style of the blocks.