The TL team have no need to apologize, isn't like they left in limbo for 6 months, and is a free service, I'm just grateful for them working on thi prequel.
Abel did indeed say that amber eyes need more time to use magic, but I don't think he proclaimed their elements were locked out for a decade, just that is a slower process than others magicians.
I think his aunt kicked him out because he was a genius, able to use magic fairly well as a child and without trining, probably people of that era already knew about amber eyes peope being good at every magic, their limitations at the start and that many demons had them too, she feared him as a monster for that.
In re;monster there is a similar species, hybrids between humand and monsters, feared by both parties for having the best traits and more potential, but even being savages and prone to slaughters, the MC quickly realized the latter was because most, if not all, hybrids were abandoned and tormented by a young age and therefore turned on normal people after getting some levels as revenge.
At least I think this is what the author wanted to make us believe.