"Lach" versus "Lecha"

In the old Kippur books (da Silva Mendes 1771 and first edition of Mulder 1850) we see "lach". In the current edition (Mulder 1876) we see "lecha", see picture below of one example: left Mulder 1850, right Mulder 1876.

In the introduction to the Mulder 1876 edition, D.R. Montezinos writes: "all expressions towards G'd in the feminine, we have changed to the masculine, except at the end of a sentence". However, this change has not been adopted by the community. This can be heard in all recordings (example SRP and example NN).

Mulder, left: 1850, right 1876