I have already been working on the batch file and used your suggestion on the CD command. I have also already removed the PAUSE commands. I put those in as I thought the batch file was executed too fast for Win10, which is not the case. Works like charm: no rename failures. Failures in the past may probably have been caused by incorrect security settings (my weakest OS knowledge).
As for your other suggestion about updating Enderal, I would suggest not doing so in the way you mentioned. I keep my Enderal folders as clean as possible, that is without extracting BSA files or copying mod changes. When done editing a mod and before testing, I create a BSA file with the CK if needed and only copy ESP and BSA to Enderal's Data folder.
Only the EnderalData folder within the Skyrim folder will contain possible needed extracted BSA contents, such as scripts, meshes, textures, face gen data, etc. That way you will test your mod (ESP/BSA) in the same way as used by a subscriber to the mod. I am planning to do the same for Skyrim (which I should have done over 8 years ago). For backup purposes I create an archive with 7z and store it outside the "Program Files (x86)\Steam ..." path.
I also have started creating an instruction manual, which I could add as a PDF and/or maybe a guide in the Steam Community guides section.