I'm not keen on the fantasy alien life either. The fact that they all look like sea-life makes me wonder if there was an attempt to appeal to the sub-nautica crowd. Thankfully, they are locked up inside those Lagrange clouds, so I can choose to ignore them if I wish, and get on with enjoying the other more realistic aspects of the wonderful galaxy model.
"Stellar phenomena" appears to be Frontier's catch-all title for "Things in Space", which is highly misleading, as I was expecting proplyds, contact accretation disks, etc for example.
I'm not sure if it is just me, but the Codex seems more like a catalogue of stuff to find rather than anything else. I actually can't see a list of the things I've found in it, though it claims that I have found a certain number of items, I've no idea how to make it show me the list of where and what those things are! The things I have "confirmed" rarely tie up with the locations I have actually found them in, and it only seems to list a single location for confirmation. I'm willing to accept that I just don't know how to use it, but it doesn't make itself obvious!
The Codex really is quite a bit different than many of us envisioned. It is indeed just a list of things that can be found. Nothing comprehensive about it. It will show the very first discovery of a particular type in a particular region. That is what shows up as reported. Once something has been found, that is the only time it will show up in the Codex. One the player has found the same type of thing anywhere in the region, it goes confirmed. That is the one and only thing that gets listed there for the player. So at most, each entry will show two entries. First reported, and confirmed. If the player is the first one to find the thing in the region, they will only show one entry. The Records in the players confirmation entry in their Codex does not update or change. It only shows the stats of the confirmation system, and indicates them as records.