I’m American and “spelled” is correct here. I concede that in other parts of the world, spelt is acceptable.

It’s true; the American English past tense form is spelled. In other varieties of English, both spelled and spelt are common.

https://www.grammarly.com/blog/spelled-spelt/

Regarding incorrect versus wrong, it’s the adverb. “Spell” is a verb, and you need an adverb to modify the verb.