Verified the special group names are present in the data-mw-group attributes as produced by Parsoid Cite extension.
Verified that T246761 (on Apple iPhone 6+ with latest Wikipedia iOS app), is still producing the correct format for backlinks on that closed bug.
Notes: Parsoid Cite extension must deviate from Core Cite extensions handling of special group names such as lower-greek, so that VE gets numeric counters instead of language or style specific counters that it would not be able to continue to extend with additional counters of the same format. As such Parsoid Cite extension relies of CSS to see the data-mw-group attribute having a special group name like lower-greek, and provide custom format counters for display where needed. Mobile applications must provide equivalent detection and display of custom counter formats.