Hi @generalfault, thanks for your patience.
So, unfortunately the decision was made a while ago not to prioritise the development of future firmware for the I-12 series that would support the new Tobii Core SDK. Instead focus has been on delivering the next generation of I Series trackers which naturally will indeed work in conjunction with the Tobii Core SDK.
Therefore, should you intend on developing exclusively for the I-12 platform, you would need to work with the deprecated Gaze SDK or assistive TEC SDK, both of which are no longer serviced or supported.
Accordingly, given you have already a 4C tracker, I would suggest you continue your efforts in development using the Core SDK using the 4C with the objective of I-series compatibility further down the line.
That being said, as I am unsure of the exact intentions you have in this project, perhaps this solution may not be appropriate for you. This being the case, please let us know and we will see if a possible solution can be found involving the older software, although this is not a recommend route. Apologies for any miscommunication previously with respect to camera compatibilities, however business level decisions were made that altered this paradigm. Thanks for your understanding.