I am not very sure about the effects of changing the nationality because I have done it only few times. I think that the mother nationality of the player defines his abilities. changing it doesn't increase or decrease these abilities that were defined by the system at the time the player was invented. (This opinion is based on 5 trials to change nationality only).

Playing 42 seasons should make you more experienced than me unless you tank a lot however I would like to hear your observations regarding the changing of nationality since you have do it ... so what do you think ?

Regarding changing your nationality as a manager which of course changes the nationality of the youth academy , does it affect the abilities of your youth players ?
i have no data to answer and i think most of us don't because most managers don't use youth players in their team since they are below the average level and tend to sell them or keep them on the benches just for the training bonus...

Regarding the Serbian / Irish/ Scottish / English and Welsh players ... I'm saying they are in general good players and this opinion is based on my experience with such nationalities. Is this related to Nordeus location ? I think so because its two branches are in UK and Serbia so it's employees are from there and it would be absurd if they
don't push the abilities of players holding their nationality

I had bad experience with Indonesian / Thai / Egyptian / Saudi / Ethipian players to name few of weak nationalities that i tried and I learned not buy them even if they were above 90% and even at young ages because they let me down many times...

Now I only chose players from the top 20 countries according to FIFA ranking from Auction list.