Can you retrieve an enemy's attack IDs with plotscripting?

Yes, you can.

All enemy data that you enter in the Edit Enemy Stats menu can be accessed with commands read enemy data and write enemy data. Commands like get enemy stat are wrappers around these commands.

These commands access raw enemy data directly. Only some items of enemy data have constants defined in plotscr.hsd (such as enemy:gold). For the rest, see DT1.

For example, to read the first normal attack from the enemy with ID enemy, you would use

normal attack 1 := read enemy data (enemy, 92) -- 1