Release candidate 2 is now available:
https://betas.ankiweb.net/anki2.1.54.html#release-candidate-2
It introduces a bug with adding that will need to be fixed in rc3: Selected field is not clearel
rc2 should fix the issue where the mapping was not recalculated after changing the delimiter. While we could potentially remember the selected notetype and deck in the future, a better way to handle this on your end is to specify the desired settings inside your text file, especially since you appear to be generating the text file with a script.