Welcome, @Community member, to the community!
Although the STM8 are very old, you can of course program them via Command Line with the ST Visual Programmer. For this purpose the program STVP_CmdLine.exe is used, which can access your ST-LINK/V2 directly.
Attention: please install in a directory with short length, without spaces in the directory names and write access for normal users, i.e. without admin rights.
Good luck!
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/Peter