when to use den or det is really annoying - if I use the wrong one they should just call it a typo
Why does spanske have the trailing 'e' here? It does sound natural to me, as we have the same nrule in Dutch, but I haven't encountered a lot of cases where it applies in Danish.
It is a general rule that an adjective gets that "e" when it goes with the definite form of the noun, i.e. when it stands between den, det, de, min, din, etc., and the noun.