It took me more then 8 hours to find my perfect NFC ring setup. I share this with you and hope, that it will save you some time.
Instead of NFC Ring Control I use NFC Tools (https://play.google.com/store/apps/details?id=com.wakdev.wdnfc).
Language selection does not work in NFC Ring Control. I switched to German and it worked. The next time I started the NFC Ring Control app, the language displayed was English again, but in settings German was selected.
NFC Tools provide more information about the NFC tags on the ring. I found out, that each tag can store 137 bytes. With NFC Tools I wrote a VCARD to the black tag, because this is the tag, I keep on the top side of the ring. First I left the white tag empty, but when I used the tag to unlock my phone, a popup was displayed, that a new NFC tag has been detected. So I filled the white tag with an app link to start my current launcher.
Instead of NFC Ring Unlock I use NFC LockscreenOff (http://repo.xposed.info/module/pk.qwerty12.nfclockscreenoffenabler)
My Nexus 5 is encrypted. On encrypted phones it is not possible to disable the stock lock screen (it took me a couple of hours to figure that out).
With NFC Ring Unlock I had two lock screens then. First I had to unlock the stock lock screen, then I could unlock the NFC lock screen. With the Keyguarddisabler (http://repo.xposed.info/module/com.lr.keyguarddisabler) of the Xposed Framework (http://repo.xposed.info/module/de.robv.android.xposed.installer) the stock lock screen is displayed only once after reboot, which made the NFC Ring Unlock the only lock screen. Problem solved? Not really. When I turned the screen on, first the current app is displayed and it takes a while till the NFC Ring Unlock app is displayed. The NFC Ring Unlock lock screen has no widgets, so to start the camera I have to unlock the phone and start the app. With the stock lock screen, I can start the camera directly. I removed both the Keyguarddisabler and NFC Ring Unlock.
Finally I found the NFC LockscreenOff module of Xposed. This adds the missing NFC tag unlock function to the stock lock screen. Its features are quite similar to NFC Ring Unlock.
Now I am really satisfied with my setup. I love my NFC ring, it's very usefull and cool show off.