Is saying "Allahumma salli 'ala Sayyidina Muhammad" a gross linguistic error because it addresses the feminine, and the correct form is "salli" by omitting the weak letter?

The common linguistic practice is to drop the yaa’ from the imperative verb when addressing a single male, as in the Almighty’s saying: “And pray for them.” Adopting this is more appropriate, especially if other approaches lead to ambiguity. Nevertheless, there is an audible linguistic practice where the yaa’ is retained to fully articulate the kasrah. This supports Qunbul’s recitation of “Indeed, whoever fears Allah and is patient” (12:90), and some poetic examples. Al-Khalil ibn Ahmad al-Farahidi interpreted the Almighty’s saying: “And that the mosques are for Allah, so do not invoke anyone along with Allah” (72:18) based on this, by retaining the waw, even though it is for jussive.