I agree that for the Aredhel/Eöl/Maeglin story, we should certainly begin with the text as written in the published Silmarillion. There may be room for minor changes or embellishments, as well as additions that serve the purpose of the story we've been telling all season.
One such addition for consideration would be - is Curufin alone when he confronts Eöl, or is Celegorm with him? We are of course going to see both brothers defending (and losing) this land in the Dagor Bragollach, so showing them both here in this episode may be a nice way to situate them geographically for the audience, and give Curufin someone to talk to before Eöl arrives. There is one wrinkle, however - if Huan is there, following or stopping Eöl would be very easy. The audience may be more inclined to ask why Celegorm and Curufin are not tracking Aredhel if Eöl truly is 'right behind her.' Curufin's seemingly passive and restrained reaction may seem even more out of place if his brother is with him.
Another issue is the question of whether or not Aredhel's return is considered a miracle. Obviously, everyone is surprised in the book. But we left her bloody cloak behind, so she's been presumed dead in a very Joseph and the Coat of Many Colors way. So, her return is as if she's not just returned after a long absence or after being lost, but also after being declared dead. Her reunion with her brother Turgon should therefore have a heightened element of unexpected joy to it, as does the reunion of Joseph with his father Jacob in the Genesis story.
There are a few details we have added to Aredhel's story, and those should probably come up after her return to Gondolin.
One of those is that she was explicitly and publicly given a mission to speak with Fingolfin before she left. She has now returned...not having spoken with Fingolfin. So, her uncompleted mission should come up, and there is a question of how that will be handled. After all, the world is a dangerous place and I got attacked numerous times is certainly a credible reason why she never carried out her assigned task, but someone should probably ask her about it at some point.
Another is her disagreement with Turgon over his interpretation of his mission from Ulmo. He didn't understand her complaint before she left, and is unlikely to have changed his view now. But she's gone through some things since last they spoke, and may be more favorable to accepting Turgon's goals as 'good enough.' She had wanted more, but she has to realize that Gondolin is not nothing, and is in fact better than nothing the way it is, and preferable to her own failed plans that went nowhere. Acknowledging her own failures might include acknowledging that she jumped the gun and did not wait for Ulmo to indicate that it was time to take action. So, while she may still believe that the Gondolindrim should be preparing and getting ready to help the Noldor in the fight against Morgoth...she's likely to acknowledge that Turgon is doing it right in some way. Hopefully, they have an opportunity to discuss this and reconcile on this point prior to her death.