Love the mod, btw, and it's the first mod I enable when starting a new modded run. The one thing I don't love, though, is having to manually place and walk into a couple hundred factorissimo buildings for every single individual city-block of my base, just so my robots can fill the things with their copy-pasted contents. I'm not asking for something silly like letting robots enter the buildings from outside, but perhaps there could be some way to fill them without us needing to enter every single one of them - not just to place a logistic chest, roboport, and a blueprint; but rather not at all.

(the rest of this post is just my idea on how something for this might work)
I write mods for other games, but sadly not Factorio... so this is just a free thought you can steal if you like it. I was envisioning something like a giant building/assembly machine with a few chests that are logically a part of it, similar to how LTN has a lamp and combinator "attached" to a train station. First, we'd put an already-filled factorissimo building into this suggested loader/filler for it to copy from (to blueprint). The first chest that's a part of this loader/filler would take factorissimo buildings to paste the copied template as ghosts inside. After such, scan the inside for ghosts and put the missing contents as a logistics request using the second chest. Using the contents provided by that second chest, put the contents into a temporary logistic provider chest inside the factorissimo that's being modified (decrementing from the logistics request as things get transferred), and use temporary construction bot(s?) to place them inside. The exception to the 'just put it as a logistic request' would be other factorissimo buildings, as I know blueprints rightfully ignore their contents - these would instead be provided via the third attached chest, and all would just be assumed to be the right innards. (As far as I'm aware, there's no good way to check if they're the same... so it could just be a realistic limitation. If we really need different types of sub-factorissimos with the Recursion technologies, then we could just repeat this process in another loader/filler.) Once the loading is finished, the completed factorissimo is moved to a fourth and final chest, where it can be used for... whatever comes next, be that placing it for normal use or moving on to another filler.
For the idea, I'm not thinking it would be free nor fast - even if it's just a single robot that moves at a snail's pace and the transferring of items to fill it with cost a few MJ of power per item... My point is that as long as I don't have to enter hundreds of buildings for each of my many city blocks; I'd be beyond thrilled. If I could do anything else while loading my factorissimo buildings, even if it was just stepping away from my computer, then I wouldn't feel like I'm wasting so much time (me doing a bunch of stuff for unfinished outer buildings but not seeing any physical progress in my base is rather tiring).