The repro was simple - select some text in a Text Layer, apply any SF Pro Regular font style, other than Regular itself, boom.
The reason for this, though there really is no good reason for After Effects to crash, is that there is a problem with the construction of the particular font version which confused our code and in that confusion it did something bad and triggered the crash.
That vulnerability in our code has now been fixed, but an underlying problem with the font remains and that is the bad news that I will cover next.
The issue our code has with the font is that we are unable at times to properly distinguish between the Regular instance of the front from the Italics instance of the font. This only happens, so far as we have seen, when applying a Regular font style other than plain Regular - say Ultralight for example.
What happens under the covers is that when asking for one of these regular instance font styles we instead get font data for the italic instance. This results in a weird hybrid - the font machinery combines data for Regular Ultralight and the italic data. The result is not something not quite regular, but it is not quite italics either. See for yourself:
Regular style in the first column is correct, as are all the Italic styles in the second column, but all the other first column instances have been incorrectly italicised but still struggling mightily to reflect their proper aspect.
The only solution for this remaining problem is to wait for Apple to update this font with a new version.