Hi Thomas, Mojca and Andreas,

After playing with several options as either of you suggested, I ended up with the following setups which solve partially the misbehaviour of SyncTeX in mkiv. The solution works for with TeXShop on Mac OS X 10.10.2 and the latest standalone beta of ConTeXt. 

1) I have in a file named mkiv.engine (which sits in the folder ) the following lines:

	#!/bin/bash

	export PATH=/Volumes/OK/context-minimal/tex/texmf-osx-64/bin:$PATH
	context --autogenerate "$1" —purgeall

2) As one may see I do not use the option —synctex in the above context call, since it doesn’t work correctly (beware the — shown is actually two hyphens {-}{-}…).

3) In the TeXShop Preferences, in the Typesetting pane, I have checked the radio button next to SyncTex (Tex ≥ 2010) as one may see on the attached screen capture.
For now the syncing seems to work essentially fine (although it is not as precise as when using Plain TeX, or LaTeX, but probably this might be expected beacuse mkiv is more complex).

Thanks to all of you!
Best regards: OK