We no longer have blank columns in the tech tree. That was one of the big things to solve this version and we've done it. Though there are some needs to audit the tech tree now but yeah, no more big blank columns, particularly before the medieval era.
I'm not really fully following what this option is, nor what it is you're wanting but that might be due to the fact that I never use 'show unlearned techs only' and wouldn't see any reason to because we recolor the techs that are learned.
I do have a request for a change in this python code though that is above my ability to make. I can be very specific about this:
For the main display button on a religious technology, it is currently referring to the button as defined by the religous tech in the <button> tag slot. What I'd LIKE for it to do is, specifically only for religious techs, refer to the religioninfo.xml for that religion and IF the tech is known by any civilization, use the reference in the <GenericTechButton> slot, otherwise (the religious TECH has not been researched by any civilization) use the button in the <TechButton> slot.
This is not over my head in C++ but in python I'm sure I'd screw it up pretty dramatically. So I need a little help from you or
@Toffer90 on that. This should be prerelease as the setup will be complete with the updating of the FPKs. And I just made the code do this for the other places where the religious icons are parsed, such as in the tech selection bar at the top of the main interface and the tech selection popup (I did this wrong and will have it corrected in the next update.) Such a change would go a long ways towards helping a lot to SHOW whether a religious tech is achieved by any other player in the game or not (and thus is useless whether on choose religions, limited religions, divine prophets or not on any of the above.) Again, the references to those button slots are being updated and aligned to this project on the art side right now.