Reconciling Rey Palpatine & Rey Nobody sounds good in theory, but it still reads to me that Rey being a Palpatine is the truth instead of, at best, ambiguous. If we’re going with Rey being a clone, then it’s fine, but maybe Finn needs more definitive dialogue about Palpatine having lied.

If you want to undercut the granddaughter idea and plant the idea of their being more to what he says, you could have Palpatine say upfront to Kylo that Rey’s his granddaughter:

Kylo Ren : What could you give me?

Emperor Palpatine : Everything. My Empire was not defeated…it was preserved…frozen at my command. And now…awakened. The might of the Final Order will soon be ready. It will be yours…if you kill my granddaughter.

Kylo Ren : (Confused look)

Palpatine : (smug smile)