Working on a typeface with the same workflow.
Have around 600 glyphs / 300 non-compenented glyphs and less than 50 bracked-layered variants plus interpolationWeightY — works out quite well.
Thanks for the insight Jakob, this gives me confidence in tackling it in two masters.
Have you set bracketed on these 50 or intervened with the brace trick?
If the latter, did you design more than one instance (say, regular, semibold, etc) or just the variation right before the point where the contrast needs to change?
I hadn’t heard of interpolationWeightY, and it looks like the solution might be there (just read it in the handbook).
Always mix up these two parenthesis names.
I use Additional Masters for Individual Glyphs: The Brace Trick.
With the brace trick i added a regular master only to some glyphs. Even bold looks ok if the temporary regular corrects the black-to-light interpolation.
When in doubt you always can “generate instances” and import the regular as real third master later.
Last but not least: in another projekt, also a geometric sans, i have three masters plus some braced instances to improve the bold.
So it depense on the design.