現時点では、HighSierra以降へのアップグレードが推奨されておりません。
At this time we are investigating this issue but cannot say when we will be able to implement a resolution. We appreciate your patience while we work to resolve this issue. The only suggestion we can offer you is to revert back to the previous Mac OSX Sierra, if you have the option to do so. In the previous iteration of MacOS Sierra (10.13.0), none of the items listed above were reported to occur.
https://support.pixologic.com/Tickets/Submit
フォントの仕様変更に関して、開発も承知はしていると思いますが念の為、サポートへの報告を行ってみてください。