Trident does not get any enchantments from using enchanted books or from using the anvil.
Linked issues
is duplicated by 9
MCPE-31530
Can't enchant trident
Resolved
MCPE-31554
I can't enchant the tride nd by using a anvil it gives me an x, even though I'm in creative and have the right enchanted books.
Resolved
MCPE-31562
Trident
Resolved
MCPE-31577
Trident enchanting
Resolved
MCPE-31581
Can't enchant Trident
Resolved
4 more links
This has been fixed in 1.2.13.11