I "hear" what you're trying to tell me to do, but I'm still putting too much of a hard "y" sound at the very end of the "g" before transition to the -er. I suspect this is a musculature thing. My tongue and throat aren't used to constricting in the right places to get the sound right. Practice, practice, practice. Thanks for the reply, by the way. :)
I think that what Duo needs is a course on tongue and throat gymnastics. I wouldn't worry too much about correct pronunciation; there are so many dialects in Danish, that I don't think it really matters. I have had several Danes ask me if I came from the south of Denmark, and I took it as a compliment because I'm Irish.
In Danish, plurals end either with an "e" or "er". In some cases, intermediate letters can also change, as in:
Hund - hunde = Dog - dogs.
Hånd - hænder = Hand - hands.
There is no rule dictating when letters change character, so you really must get to know them through practise.