64-bit Logic does not require the Mac kernel to be running at 64 bit to have full access to the 64-bit OS.
Under "Get Info" for the Logic app you have Logic running in 64-bits, correct?
If you are already using Logic in 64-bit mode try this:
Using "get info" set Logic to open in 32 bit, Let it validate all the plugins, close Logic, set it back to opening in 64-bit.
I doubt if there is or will be any EFI updates for older machines.