It’s not bad except you don’t need 4 copies of the same lookup table. That should be a subroutine.
If possible, there should be four identical subroutines that you feed each digit to.

You’d normally do the display multiplex in the main program, and only use the interrupt to set a flag
that is being watched by the main program to know when a second, or whatever period ticks over.
The interrupt handler should be the smaller routine.