I think the issue is quantity over quality, especially compared to how the Batfamily acted in the 90's Batfamily events or even in the 2000's.Yes they could have had him team up occasionally up with Batman but they didn't and that's fine. Tim was busy elsewhere, Bruce lost his memories for some of the new52 and there were new characters that need to be introduced to the Batman readers so they took priority.
Tim had quite a few team ups with other Batfam. He took part in 3 or so bat events/cross overs. Again not every bat family character got that.
I don't understand how you can ever view Tim as marginalised during the new52. It smacks of entitlement or expecting preferential treatment.
He already had 2 ongoing titles even Dick Grayson the Batfamily member with the longest tenure. The 2nd most significant character in the Batman narrative [he was there from jump] didn't get 2 titles.
Dick was also pretty isolated from Gotham in the new 52 due to Grayson.
The series meant to celebrate his anniversary was repurposed to push another character.
Dick's history was also badly butchered by new52 retcons with the additional bonus of higher ups hacking off an important part of his lore and grafting it on to Tim.
lets not forget, DC tried to kill him off during the new 52 yet because Tim didn't have enough team ups with Batman and the batfam and that means Tim was marginalized.
Some characters only got brought back towards the end of the new 52, some were pretty much exlied from Gotham. Showing up even less than Tim in the main Batman title, used even less than Tim in events.
You need to consider how other Bat characters were used during the new 52 period.
Consider that writers have creative freedom. They come up with story ideas and the cast of characters.
Occasionally DC mandates that certain characters have to be included. At times some characters are off limits for various reasons eg. Damian despite being Robin during Snyder's batman run was off limits due to the writer having a 10 year old son so he didn't want to write a 10 year old in violent scenes [fyi this also isn't Damian being marginalised].
That still left him with large extended batfam, Gotham characters who are well known supporting characters in Batman stories and a number of original characters.
That a lot of characters so it's understand able that Tim didn't show much in that run. It's the same with other Batman and individual batfamily writers. If they didn't have a story idea that included Tim then they don't have a story with him
Honestly new 52 didn't give us a lot of Bat family interactions or team ups. BRE and Batman Eternal were bat events so we got interactions in those.
Robin war tie ins.
Death of the family and the tie in's
B&R gave us 3 arcs with Robins interacting
Batman Inc
Court of Owls
Batgirl I seem to recall some Dick/Babs [that might have been a phone conversation though]
I feel like I'm forgetting some others.