Note: you should have Show all filename extensions checked to On. Otherwise you can get confused about the filename extensions and with what we are doing having the correct extension is critical. So make sure that you are set to Show all filename extensions.
I am fairly certain that you may need to keep the files that you create in someplace normally accessible Like the Desktop for example and then run the Terminal before you place the files in their proper place.
Then Make sure that you then place the files in the Correct Directory, I know it is confusing but the Mac has 3 Different Library Folders and it sounds like you might have put the files in the wrong place.
Update: I tried to see if the files are in the correct directory running sudo chmod 644 and with both it says "No such file or directory" like the mac doesn't read that at all. I tried to run launchctl limit and like @bourgeoisbanana said, nothing has changed.
At least according to what you wrote. I think that is the problem.
On my Mac the correct path is <Mac's Hard Drive Name>/Library/LaunchDaemons
On your Mac when you look inside the <Mac's Hard Drive Name>/Library/ do you see a Folder named "LaunchDaemons"?
Do let me know on this.
If so then Apple did not change the file structure {I don't expect that they would it would mean more than a few Popular Apps would have to be fixed if they did}. So you need to put the files in the <Mac's Hard Drive Name>/Library/LaunchDaemons folder and I would do it
after you have run the chown commands on them in Terminal and then checked them...See Section below on that part.
Note: If you don't have and use Shell Files just ignore that section, it is for those who use Shell Files. If you don't know what Shell Files are you should also ignore that section.
Once you have created limit.maxfiles.plist and created limit.maxproc.plist
Then you go over carefully to make sure you did not make a mistake, me I copied and pasted the text I provided into each file and then I changed to filename extension on each file. Anyway now is a good time to verify accuracy.
Next Run the Terminal and did the chown commands and then you should go to the Finder.
Select limit.maxfiles.plist and then type command I or go to the File Menu and then choose Get Info, you will then get a window.
Scroll Down in the Get Info Window to Sharing & Permissions: you should see in columns Name: system; Privilege: Read & Write; Name: wheel Privilege: Read only; Name: everyone Privilege: Read only
Do the same procedure to limit.maxproc.plist and you should have the same results in Sharing & Permissions as for the other file.
Note: also in the Get Info Window both files should have Open with: Property List Editor.app (default)
If you see the same things that means that you did chown commands correctly, if you don't see the same permissions that I am seeing then it would mean that you did not do the commands correctly, try again.
Once you have verified that the files have the correct Permissions using Get Info, you then should put the files into <Mac's Hard Drive Name>/Library/LaunchDaemons and then you Restart.
Everything should work then.
Do let me know how it goes. I know it is not really Simple, but it did work for me and I am sure it will work for you too.