I found the time last weekend to remove the transmission tunnel plastic console as per B&M instructions. After unbolting the shifter assembly, I immediately found 3-4 coins under it.
Further forward along the central groove in the metal bodywork where two wire bundles run, coins were lodged deep under where the CD holder is located. I fashioned a wire coat hanger into a straight long shaft with a small rounded hook tip to fish another 3-4 coins out.
After 3-4 repeated reinstallations and removal of the shifter assembly and test driving with sudden accelerating and braking motions to listen for jingle/rattles, (i didn't know how many loose coins were lost to begin with) i finally tracked down another 4 small coins that had travelled as far forward beyond the CD holder (shin level when your leg is resting against the dead pedal).
I only managed to remove these with bare fingers through a tiny hole in a metal bracket under the carpeting, in combination with the modified coat hanger. (Lucky i have small hands).
I can cautiously claim success for now, unless I hear further jingling, but so far, so good. Yay.