It seems you have a typo on your sentence... you wrote “been” twice. Having said that, many combinations are valid. It depends on context. 1. I have continually been transformed. This seems to be the most proper/common way. Placing the adverb between the auxiliary verb “have” and the verb to be. 2. I have been transformed continually. Adverbs of frequency can be placed at the end of a sentence. 3. I have been continually transformed. I don’t think this is wrong , perhaps it makes more sense to place it there to make an emphasis, and you would hear people saying it in this order, although may not be grammatically correct.

Yes, the second been was a mistake.

"I have been continually been transformed." ✘ "I have continually been transformed." ✓ "I have been continually transformed." ✓

"I have been continually been transformed..." = This grammar is wrong. You only need "been" 1 time, but you can write it in either location.

You could say: I have been continually transformed... Or you could say: I have continually been transformed... The positioning of the adverb is somewhat flexible. But saying been twice like in your example is an error. "Have been transformed" isn't really two verbs. It's simply "to transform" conjugated into the present perfect continuous tense.