So the complaints here were about the best part of the episode?
The anime did a more subjective job here, did not put things in our face in this case.
Lillie's love for Clefairy / Clefable has been explored literally since the series began. Through the Clefairy doll (The first apparition was with the lure clefairy-EP005)). Many said that the doll's parting was just a reference to the games, but the thing was very different from that.
The doll has always had a sense of security for her (The fact that she sleeps with the doll confirms this). So Clefairy appears from the beginning in an indirect way.
Another mistake is to say that the thing has only been explored in two episodes. The "aether" arc was developing this all the time! And again it is by the doll that this is done (after all, clefable was not with Lillie).
A very important thing here, is that Clefairy does not represent just a pokémon that Lillie loves. She is extremely attached to the relationship between Lillie and Lusamine. The bad feelings that Lillie feels for Lusamine are related to the attention that Lusamine failed to give her (for being too busy). Lillie misses a lot of the time they play and they were happy, and clefairy (and the doll) became a big symbol of that time. (When Lillie is thinking about her mother in episode 48, she's cuddled with the doll before going to out of home). Lillie's discussion with Lusamine about the evolution of Clefairy could be explained by the feeling of rejection of change (in relation to each other) that occurred shortly after Clefairy evolved((Even though in episode 045 it gave the impression that she had been irritated with Lusamine by evolving Clefairy, episode 53 confirmed that it was only emotional (with Lillie playing with Clefable))) It is even understandable Lillie's rejection of Lusamine's affectionate displays, because it is not like it used to be, it seems more like a treat (a way of saying, "I'm still here"). That way, the doll is a memory of a beloved Pokémon, and also of a past that she really misses.
When Gladion said that Lillie could not carry much in her backpack, Lillie made a point of taking the doll. On the one hand the doll was used to bring Clefairy back, on the other, we could interpret that part of "EffortfuLillie" also refers to Lillie's willingness to finally have her mother back (Not only physically, but emotionally). Since her memoirs have "returned," she is willing to go back to having her relationship with her mother by the time she became emotionally attached to the doll. So, taking the doll to take to travel is a thing with more meaning than a simple change in the look.
Thus, a flashback between Lillie and Clefairy / Clefable was not necessary before this episode. The anime showed what the Clafairy doll represents to Lillie. And in that episode was focused the friendship between Clefable and Lillie. (In previous episodes, like 49, this had already been shown).
The triumph of this moment was to show for the first time the relationship of friendship itself between the two, not only what it represented. There was no reason for Lillie to be reminded of Clefable before that, she was with her mother, safe.
The conclusion of this arc of Lillie at first focused on the Clefable, then focused on Lusamine closes well everything that the series (and especially the arc) showed about the meaning of the doll (a deep feeling of longing). (which turned into a feeling of hope)
Again, the soundtrack was spectacular. The problem itself was the animation that was well below what it should be.
