When designing Cyrillic, some of the italics can take vastly different forms.https://commons.wikimedia.org/wiki/File:Cyrillic-italics-nonitalics.png
But in some Cyrillic designs, the italics are oblique and the letterforms don't change. I'm trying to figure out the borderline where these traditional forms would be inappropriate.
If I were doing an old timey Cheltenham sort of design, I'd go with the alternate (traditional) italic Cyrillic forms.
If I were designing a square, high-tech spaceship font, I'd likely go with oblique forms.
But I'm not sure where the borderline is. When I look at Paratype's italics, News Gothic has oblique forms while Humanist 521 and Journal Sans have traditional forms.https://www.myfonts.com/fonts/paratype/news-gothic/italic/glyphs.htmlhttps://www.myfonts.com/fonts/paratype/humanist-521-bt/italic-128520/glyphs.htmlhttps://www.myfonts.com/fonts/paratype/journal-sans-new/italic/glyphs.html
It seems like the borderline has to do with "how italic" the a-z is.
1: Just slanted
2: A bit more italic: the f has a descender and the a in monocular
3: Somewhat italic: curls have sprouted
10: Full blown Caslon
Bell Gothic has a italic that would be somewhere between 2 and 3 yet it has the traditional Cyrillic italic forms.https://www.myfonts.com/fonts/paratype/bell-gothic-bt/italic/glyphs.html
And Futura has oblique forms.https://www.myfonts.com/fonts/paratype/futura-book/futura-medium-italic/glyphs.html
Is it a case of "how humanist" the design is?