Yes, you said it right, on paper Croatia is better than both Wales and Turkey, but Croatia has always had big problems with weaker national teams in qualifying for major competitions.
The qualification for the last European Championship started with a defeat against Slovenia, and the qualification for the League of Nations with a defeat against Austria at home.
After that defeat against Austria, Croatia beat both France and Denmark away from home, so it was once again shown that Croatia always plays the best against the strongest national teams and always has serious problems against weaker teams.
I don't know if this is due to the mentality of the Croatian players, underestimating the opponent or some other reason, but I expect similar problems in these qualifications as well.
BTW, I wouldn't call Austria and Slovenia as weak teams. But I get the point. Both these teams can't be compared to sides such as France. BTW, I am surprised that you have grouped together France and Danmark. The latter are a shadow of their former self and are on a downward slide since the last one decade or so. I won't be surprised if they fail to qualify for the Euro 2024 and FIFA 2026. It looks like Croatia performs the best when they are the underdogs. When they are the favorites, the performance go down.
I am not comfortable with one of the factors within the current Croatian team. There are very few young players and most of the star players are over 30. Dejan Lovren, Domagoj Vida, Luka Modrić, Ivan Perišić and Andrej Kramarić are all in their mid-30s or late-30s. This is like a double edged sword. It gives them an advantage in terms of overall experience. But at the same time, absence of younger players may prove costly while playing against more athletic sides.
Yes, that is probably part of our mentality, that we always play our best against the strongest national teams, and that we are always particularly motivated, but against weaker teams we somehow always play more relaxed and with less concentration.
As for the national team itself, I would not agree that too many old players play. In fact, I think that our national team is a good combination of experience and youth.
On the one hand, there are older players like Modric, Brozovic, Perisic and Kramaric, but on the other hand there are also very young and promising players like Livakovic, Majer, Pasalic, Vlasic, Stanisic, Guardiola... so I don't think we should worry about the future of the Croatian national team