So...the main part of your argument is invalid because this is not a commoner becoming a noble. This is a noble being rejected from the family, then after the recommendations the family is recognizing them as family, reinstating them into their noble lives.
To be
re-instated they'd have to have been considered nobility in the first place, or even accepted as a member of bloodline which in most cases these were bastard children or children of denounced lines in which case is being a commoner. You were denied in name, and continued to be until you were of both use and proven to be of a bloodline even today there are common people who if were to research their ancestral lines could petition for recognition of a noble line. The Tudor line it self produced so many bastards it's predicted some still exist though the royal line is considered dead.
Adventurers are considered to fall into this category, and yet they are still commoners, a commoner with possible claim but commoner nonetheless.
As for me, I went from advie to noble very quickly, it seemed far too easy.
