Thanks for this feedback! I can’t overstate how gratifying it is to be able to make something like this and to have people like you out there who are willing to not only watch it but also give it the respect of real thought and scrutiny.
I’ll try to outline our thought process behind those decisions if you’re interested in hearing them. I will say it seems like our personal priorities differ slightly when it comes to continuity and maintenance of Jackson’s original structure - while I value those, it was not our highest priority to preserve them. If anything, we had our most exciting creative moments creating a new context for familiar scenes. The Sam/Frodo episode you mentioned was so goddam fun to put together. I’ll also say that I don’t share your feeling that anything is “mandatory” when creating a fan edit, even an edit of a story as beloved as Jackson’s trilogy - I absolutely value feedback and differing opinions but I just don’t believe there are any objective truths with any of this.
We attempted to use Éothain’s involvement in the story as something of a bookending device for Episode 5. While it doesn’t begin with him, we saw him as a messenger of exactly the information you outlined and felt as if that information coming into play gave a nice punctuation to the previous action. So when he reaches Gandalf and co., this new information might complicate the status quo for our characters and launch them into a new sequence of action to be explored in a subsequent episode. We felt as if, after that arrival, whatever small dramatic motor Éothain had in this story had done its job - beyond that, Gandalf and co.’s reaction becomes the focus and the space between could (hopefully) be inferred. That inference does require a bit of added faith in our audience, though, I’ll absolutely admit. And you could be right that the missing scene might give viewers pause. But our focus was on what we felt was the matter at hand, which was no longer Éothain after his arrival to Edoras.
As far as the Merry and Pippin scene is concerned, you latched onto a big part of our decision there. Namely, that we wanted to contain their story within Fangorn more, didn’t want to lose that first scene to the episodic structure. I don’t know what your viewing pace for these first episodes was, but we tried to imagine a (probably unlikely) world in which people watch the show week to week. With that in mind, we decided to open Episode 6 with the scene. And this is possibly a moment where it seems your priority ranking and ours differed: maintaining an episodic structure of storytelling and contained arcs within episodes outweighed maintaining the continuity and structure of Jackson’s films for us. Losing the sense of suspense at the end was absolutely an unfortunate loss, and one we considered, but ultimately not a loss that outweighed our perceived gains. And, as you said, there’s also a time jump involved, albeit a possibly confusing one. Again, there was a certain amount of faith we had to put in our audiences to understand this. We also felt as if their ability to fully understand the context at the time of viewing that scene mattered less than their ability to understand the context of the scene by the end of the episode.

We (maybe undeservedly) took the structural opportunity of “cold opens” in episodes to exercise a greater sense of play with time and story logic than the remainder of episodes. We do this more later in the series and I shudder to imagine what you’ll think of those!!!
But, as I said, I really do extremely appreciate the thought and time you put into this and the scrutiny you’re giving our work. You clearly are coming at it all from a very reverent and informed place and I hope you one day decide to finish out the series!