I think the last few discussions about booting into original firmware from GM9 got so heated that they were nuked entirely. There is the aforementioned sticky thread at
https://gbatemp.net/threads/about-removing-b9s-and-the-safety-test.541718/ that discusses how it is not necessarily a reliable "safety test" for uninstalling.
I am fuzzy on the specifics, but I think when you use that method for booting into original firmware, it removes certain protections that could feasibly allow b9s to get overwritten in a system update and cause some sort of brick.
https://3ds.eiphax.tech/issues has a detailed guide for how to troubleshoot problems with steelhax, but pichaxx is a smaller download, works more reliably, and is just as easy to install, so there's no reason to use steelhax at all. And as many have pointed out, there's not much reason to forget about pichaxx as well and just install CFW.
Anyway, if you were using steelhax on a U-region unit with 11.7, it would still work under 11.14 without making any changes. The payload changed for E-region units when 11.10 was released.
(The funny thing is, Nintendo could easily keep anyone from installing steelhax ever again just by removing the 1.0 version of Sub Wars from the eShop and leaving the 1.1 version up for download - but they never have.)
No one seems to recommend the Sky3DS anymore. (I think you'd have to setup an EmuNAND to get it working anyway.)
If you are launching the Homebrew Launcher with Sub Wars, then you only have "userland" homebrew and cannot run FBI or install any CIAs. Installing full CFW requires following the instructions at
http://3ds.guide . The first step, Seedminer, is the same in either case - that's where you add a bot to your Friends list. But things diverge significantly after that.
(Steelhax stops working after you install CFW. Rosalina is used to access the Homebrew Launcher instead in that case.)