For me, the adaptability thing is an anxious way of thinking based on fear. Nobody likes going through bad spells but sometimes it's a necessary evil. When you're attempting to change a culture or mindset within an organisation, you just can't flip flop and change your mind on your principles or beliefs. There's no certainty about any managers philosophy working at a club but I certainly don't want Amorim to abandon what has made his previous tenures so impressive when we've got a squad that just isn't up to it regardless of formation.
4-3-3, 4-4-2, 3-4-3, 5-3-2, It doesn't matter, we're not good enough, we're not physically up to it or dynamic enough and we're not going to do anything this season that matters anyway beyond sneaking a Europa League (where I'd actually argue we've probably been most successful due to the lower physical floor of the competition, we're still the only undefeated team in Europe this season). So there's no real reason to change his approach in Europe, or there's no reason for anyone to ask him to do that in my opinion anyway.
I think people are underestimating what Amorim is actually doing here on the whole. There's a lot of psychological evaluation taking place of the squad. It's about more than just, can this group play this formation, well maybe we should switch to 4-3-3 as they are struggling. It's just as much about the mentality of the players, he's challenging them. He's saying you're not used to playing this way, system wise and physically. Can you do it? Are you willing to be coachable? It's essentially survival of the fittest within the squad. For his tenure so far and until the end of this season, for this group of players it's 'can you show me you can be part of change at this club, do you have the mentality and energy for that?'. It's everyday he'll be watching as well. Can you train like I need? Can you behave like a representative of this club? Can you take the instructions I'm giving you and implement it on the pitch? Are you physically up to it, or are you willing to put in the effort to be physically up to it? (Some will never manage that). This could completely blow up in my face but I truly believe if we can do some good business in the summer simply by raising our physical and mental floor with incomings and departures, we will be so, so much better under him.