Welcome to the community!
Generally speaking, this is a ‘help us help you’ sort of forum. Everyone that responds is volunteering a bit of their time to help, so if you have any progress started on your script or thoughts about how to implement what you’re looking to do, that’s going to go a long way to getting a timely response back.
A few questions since I don’t usually do ceiling systems.
What does a t-bar family look like? Do they need to replicate the wall-to-wall dimension of the display lines you’d see in Revit?
Is it general practice that you center the tiles on the centerpoint of the room to minimize tile usage?
The last time I looked into ceiling systems (as part of trying to place air terminals), I don’t believe the line elements in the ceiling systems were accessible.
Some context (from 2018). At that point in time, the fill pattern lines weren’t exposed to the API. I can’t find threads that suggest that’s changed since. So you have to replicate the logic in your script instead of lifting the lines directly.
If you’re following the strategy of reducing tiles used, you can replicate the lines yourself based on knowing the center of the room, the perimeter boundary of the room, and the X/Y spacing of the lines.