You just need the files from your old card, that's all. Everything you have already done is there (you moved files to SysNAND since it loads Luma without the card), so don't worry, just backup all the files from the SD card for now.
Luma default boots from the SD card, reason it's not working for you while it works without the SD card (in which case it boots from SysNAND). To boot Luma with an SD card, simply have the required files on it and it should work.
What do you mean solely? There is literally no difference between having it on the SD card and SD card+SysNAND besides being able to use it without the SD card, nothing else. It's not worth it trying to undo the SysNAND modification now since you already have done it.
The required files are the ones listed in the guide. It tells you what to keep and what not to keep once done with all steps, so do it when you finish the guide. For now, leave all files as is.
