After looking it over, I assumed the character is level 5 and compared the maximum amount of damage that could be done and how often you can do it. Basically, as the rules are written, a level 5 paladin can do 2d10+6d8+d4+3xstrmod damage twice per long rest. The second time would actually be 2d10+8d8+d4+3xstrmod.(49+)
This amount of damage is much higher than the rogue or fighter or wizard damage in a tight burst. (8d6 for the wizard). However, the DMG suggests that a single target level 3 spell can do about 5d10 damage. (27.5) Which could, in theory, be twinned by a sorcerer to do 10d10 (55), but no such spell is currently available to the sorcerer to do that with.
This is limited to two times per long rest. During all other attacks, the Paladin would be doing 2d10+d4+3xstrmod.
I don't think it's appropriate to house rule an AL game, but this is certainly a larger level 5 nova than any other. And I'm rather surprised the errata didn't w clarify for smite to only be viable once per turn/round. While the nova is greater than any other available at level 5, it seems to me that it is within the damage limit of would be allowed with the highest damage spells.(If such spells existed). It should be noted that skills are balanced over the course of a day, with 6-8 encounters, not just single hits.
This has been confirmed by Jeremy Crawford.