FrameNames.Action = {
"VFLButton", -- OpenRDX
"DominosActionButton", -- Dominos
}

I just added above line into Hekili\Libs\SpellFlashCore\SpellFlashCore.lua to enable SpellFlash on Dominos Action bar. See if you could update and release.

correct. After adding Dominos line, I can have SpellFlash working with Dominos action bar.

Did you mean to note this on the SpellFlash library?

For instance, I got the name of one of Dominos action button name by following command.

/print GetMouseFocus():GetName()
DominosActionButton13

Just realized this is for Dominos addon. Sorry for the confusion.