In other words for me Girona is not fully ready to compete in the Champions League. I mean Girona goal this season is just to gain more experience by playing against big European teams. Their first season in the Champions League is not about whether they will advance to the next round or not, but how much Girona can learn from their opponents game. The final result even if Girona loses will not be considered bad.
Their first season in this competition is more about gaining experience and understanding the intensity of competition that takes place in the UCL with against big teams, so indeed they can't do too much in the UCL when facing strong teams, like as Feyenoord, PSG and eindhoven who have experience and better performance in the UCL, however, like your said, the experience Girona have gained from UCL games this season will be invaluable for their future development, although there is no guarantee that they will be able to qualify for the UCL again if remember their inconsistent form in La Liga so far.
Yes true, for their first ever participation, they did alright and the fact that they are even here is more than enough, so there isn't really anything that would be all that much of an issue, we need to consider how that would look for the future and how they could improve on what they did this season. If you ask me, they did alright last season but this season they do not look that great, and not just in UCL, they are 8th in the league as well, which isn't great but at the same time if they finished 8th last season, we would have said that's good, but because they finished third place last season which was totally unexpected by anyone, I feel like that makes people have higher hopes for them at La Liga.
So while the UCL scores are normal for a team that is going there for the first time, I feel like they need to finish at least fourth place, and go to UCL again to make sure that they do better next season, if they join UCL once and never again, then that's not good at all.