The colleague was wrong. Leave entitlement for adoption or maternity leave is the same.
The legal minimum is the same. Employers can, and do, top up only the maternity leave/pay and make no supplements at all to the adoption leave/pay.
Neither we nor our children's birth parents were made of plastic. I dislike the phrase "real parents" in general not because I'm going to fall to pieces if someone implies I'm not a real parent - I'm a grown up - but because it goes along with my DCs not being "real" and they are small DCs who do not need to hear that kind of rubbish.
It is however mildly confusing to me, and will be very confusing to my DCs when they are old enough to understand, to have HCPs for example (and other adults) ask "do they see their mother".
Some of my adult adoptee friends like that they were told they were chosen, and some hate it. On balance, if there's a risk it will not be a great choice of words, I won't use it.
Without exception all our kids have issues that have arisen directing from their adoptions
While some of the issues you mention may well arise directly from being adopted (rather than remaining with birth family or foster carers), I would argue that most of them arose from the issues that led to a child needing adoption.
Our DCs will naturally struggle with the fact that their BPs couldn't take care of them and couldn't change their lives enough to be able to take care of them (i.e. the fact that they were adopted). But they will also struggle with choices that their BPs made that both directly affect them and led to the BPs inability to take care of them (i.e. the situation that led to them needing adoption).