As a native Norwegian speaker, I think it's sloppy work not getting the sound right. Many of the sound files are off, saying "én" ("one" - the number) instead of "en" ("a" - indefinite article). They are not pronounced the same, and if learners mimic the sound files, they are learning it wrong right from the start.
When you say it merges with the n do you mean its dropped? Similar to how British English would render car "ca:", with no discernable r (if you don't know what I mean, see the wiki article on rhoticity in English). For example here barn in BE would be "baan" (i.e. just a long a) but in AE would have a clear r.
I appreciate the clarity, I think my old ears struggle to hear the difference at times and has made me wrong in a few cases. also when you say one book and a book I understand the written difference but did not even know there was a way to say them differently. It is amazing the little things you pick up when going back over old lessons though.