ChaosWriter

Yeah, you're right. But Iwaki is just a High Class Human, he doesn't exactly know how the top leaders of Fallen Angels would fade against the strongest of the Devils. He has been rather limited in his thinking because of his lack of knowledge...

It's not like she didn't train before canon. It's just that, she still had years before the time of her marriage. With her talent, she would've grown strong enough to beat Riser in those years easily. Rais' parents brought up the date for whatever reason, making her seem lazy and incompetent when she failed to defeat Riser.

No, The name is just similar sounding to Bonney's real mom's name.

WB Pirates are nowhere near strong enough to face the true strength of the World Goverment, not yet. If you read till the latest One Piece Manga Chapter, you would know how truly strong the real powress of the WG is.

Yeah, and Rizevim learned about the other world because the Boob Fairy contacted Issei during the Loki Attack, I think. Rizevim then hatched the plan of invading the other world, so that he could become the ultimate evil of that world and also a maou? who knows, I haven't read the LNs, but through a few discord friends, I learned much of what happened in Canon.

Yes, you can use this idea as you see fit, no problem.