I occasionally see I have a new codex item, so I open it up and there is no indicator showing what the new item is. I open each category, nothing. Any chance an indicator could go beside the new codex item?

The codex if often updated if you read a new piece of information or log.  I generally just ignore it unless I have a specific question I need answered.

They game keeps you so busy learning stuff, so when I go there and have no idea what was added I have found myself not going in there either and just googling things when I need it. It seems kinda basic anyway. I could remember what a particular big ass bug looked like so when in there, no section on and no pictures anyway...so like most things I'm curious aobut...Google to the rescue lol. Though need to be careful accidentally tripping over a spoiler.

What is new is usually marked either a dot or a star I forget which the problem is the subjects aren't so you have to open each one to see what is new.  In general it seems to be the logs category most of the time which is about any piece of new information or even you trigger in the game.  I haven't gone the google route when I find something I am not sure about I just shrug and push on figuring it will come clear the more I play the game.