On the new 2.3 feature of adjusting auto-aligned glyph sidebearings, with multiple masters:
I noticed that entering =+20 to an auto sidebearing will add 20 units to all masters. This isn’t all that useful, as my caron.alt in Light is much much narrower than my caron.alt in Black.
Luckily, I found that I could use two equal signs to make per-master adjustments (e.g. ==+20 in Light, ==+50 in Black).
But it appears that these adjustments, which look fine in the Glyphs app, aren’t made in the exported font when I test it in InDesign.