You are correct in your timelines - the units that had G12s were 23 models however Ambitions had the G12 for their first year in 2022. Anything prior had the G6 so my 34RLB is the G6.
It did take me a bit to get to the right person to help me as they told me Seelevel support hadn’t been developed for my model. When Stuart was looking to get his update I reached out to one of the Spyder folks I have worked with and it seems like they have dropped some of their future development for those of us with the G6s not having the update for his or plans to do so.
Not having the update isn’t ideal but also still works fine. As you probably read in this thread prior to the update being installed (if you connect via RVC) the system will flash the readings from the old sensors to the Seelevels. Stuart mentioned that this takes a bit longer for his Eclipse (remote app for spyder) to update.
You may want to bypass the Spyder system completely and have the Seelevel installation stand alone in this way the Spyder system would still give you the OEM sensor readings and look to the Seelevel for their readings. I am not sure how deep you are into this as of yet but you may want to look at the display that has bluetooth in it which will allow you to use the Seelevel app to get readings. I installed two displays; the RVC unit in my bathroom and the bluetooth unit in my wetbay. I could use the Seelevel app (Garnet RV) to check my tanks.
Not the best answer for you but it is possible the next time you speak with Spyder you will get a different answer. Their used to be an extremely knowledge support person named Gordon and was a wealth of information and had all of the appropriate internal contacts. After he retired I have had some issues getting the answers I need although they still have excellent support just missing some of that earned knowledge.