1. Create a file "1.txt".
2. Run gvim.exe -u NONE --cmd "set encoding=utf-8" --cmd "language messages Russian" 1.txt
3. Repeat step 2. Gvim outputs an E325: ATTENTION message:

Обнаружен своп-файл с именем ".1.txt.swp"
              дата: Âò èþë 16 01:07:25 2019
         имя файла: C:/Users/***/Downloads/1.txt
           изменён: нет
      пользователь: ***  компьютер: ***

при открытии файла: "1.txt"
              дата: Âò èþë 16 01:05:01 2019                                     

(Personal info replaced with "***"). Please note the "дата:" ("dated:") lines: the "Âò èþë" part should be "Вт июл" (which is short for "Вторник июль", the Russian for "Tuesday july").

If at step 3 I set "language messages English", i.e.
gvim.exe -u NONE --cmd "set encoding=utf-8" --cmd "language messages English" 1.txt ,
the day of week/month part is still displayed incorrectly, in the same way:

Found a swap file by the name ".1.txt.swp"
             dated: Âò èþë 16 01:16:26 2019
         file name: C:/Users/***/Downloads/1.txt
          modified: no
         user name: ***  host name: ***

While opening file "1.txt"
             dated: Âò èþë 16 01:16:17 2019                                     

Windows 10 Home 1803 (Russian)
gvim_8.1.1674_x86.zip