For the record, here is my solution until the issue is fixed for RTL.

\setupformula[distance=0pt]

This causes the formula numbers to be at the proper place for left/right as
well as LTR/RTL.  It prevents some custom placement of the formula number,
which I do not care about.

—MHB

On Mon, May 15, 2017 at 11:09 PM, Mohammad Hossein Bateni <bateni@gmail.com>
wrote:

> Hi Hans,
>
> I recall something like this was reported a few months back, and you said
> you were reworking math alignment mechanisms at the time.  Now that you're
> getting ready for the Tex Live version, I want to bring attention to this
> issue once again, in the hope of getting it resolved.
>
> Formula numbers are not placed at the far end when in RTL.  Here is a MWE:
>
>
> \starttext
>
> \input knuth
>
> \placeformula
> \startformula
> E = mc^2.
> \stopformula
>
> \righttoleft
>
> \placeformula
> \startformula
> E = mc^2.
> \stopformula
>
> \stoptext
>
>
> Attached is the result from context version 2017.05.14 19:09.   Using
> \setupformula[location=left] gives similar results with directions swapped:
> output is as desired in LTR but slightly off the edge in RTL.
>
> Thanks,
> MHB
>