Well, singing in a false accent to me is wrong!
For you, "wrong" might include singing out of tune, playing the wrong chords, a chiche arrangement, predictable lyrics...

As I've said before, Adele can never be the "real deal";
however, some day the "real deal" will emerge from the UK.
Someone who can sing music born out of Americana but layered with British sensibilities...and a British accent,
Because without the accent it's always going to be - at least - one step removed from the "real deal".

Indeed, I predict that there will come a time when music fans will shake their heads in disbelief at the acceptance of these phoney accents.