A quick and dirty RRset management web page is available at https://webadmin.on.dedyn.io/. It is quite primitive (errors from the API appear in alert windows), looks ugly, but is functional enough for me to use. Requires a modern browser, does not work in IE11!
Feel free to use it too.
If the API is too confusing for you, you should probably wait for the official web management interface instead.
As the official web interface is live now, probably use that one instead. My website does not check whether the RR type is valid, it just includes a list of common and not so common RR types. You will see if it works when you receive the error message.(or not).
Apparently, that is not clear enough to GUI users. Do you have suggestions on,
how to improve that?
I would suggest adding an “(other)” or similar entry to the drop down which will clear the input field and place focus there. Combo boxes (combined edit and dropdowns) have been common in Windows 3.1 GUIs but in my experience most modern software do not use them any longer so not everybody will notice the text cursor appearing when hovering over the dropdown arrow.