PLURAL "abuse".
Sorry to say that. The trick to abuse GENDER with a special case "0=an anonymous user" will fail on languages not having PLURAL.
- mobile-frontend-last-modified-with-user-days ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 day|$3 days}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-hours ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 hour|$3 hours}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-just-now ("[$3 Last {{GENDER:$1|edited}}] just now by {{PLURAL:$4|[$5 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-minutes ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 minute|$3 minutes}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-months ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 month|$3 months}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-seconds ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 second|$3 seconds}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
- mobile-frontend-last-modified-with-user-years ("[$4 Last {{GENDER:$1|edited}} {{PLURAL:$3|$3 year|$3 years}} ago] by {{PLURAL:$5|[$6 $2]|0=an anonymous user}}")
That's not true. Explicit PLURAL overrides everything. It's definately not GENDER abuse, as GENDER isn't relevant for the construction of the message in the location you're pointing out.