InDesign should apply variating substitutions from rclt
Variable fonts may contain location-dependent substitutions, but the
rvrn feature runs too early for many real-world substitutions. The solution in font-making land has been to use the
rlig features instead, but at least the former is not supported by InDesign. This is a major headache for e.g. Arabic.
Technical discussion about this at
This is super frustrating.
Problem in other Adobe apps as well.
Making weird hacked fonts to try to work around Adobe bugs is irritating, seeing as the build chain doesn’t natively support the wacky feature duplication required.
However, coding this with 'calt' instead of 'rclt' does work in InDesign at least (and probably other CoolType apps).
This is more of a hack, as these are usually not things one wants users to be able to turn off (potentially by accident). And of course fonttools does not support this so one would have to do it as a post-processing step. But it is definitely better than “doesn’t work at all in Adobe CoolType apps like InDesign, Illustrator and Photoshop.”
I have a pre-release font using 'rclt' in the way outlined by Nikolaus above.
It is a next-generation version of a widely-used typeface. Unfortunately 'rvrn' is not an option in this case.