Well, there
https://4pda.ru/forum/index.php?showtopic=204708&st=20#entry104089976 somebody saved all PRS-650 related stuff,from back,when those were new devices,i managed update boroda to version 1.05 m,that also updated original Sony software to version 1.0.00.14080 without nagging (update_bat,no exe updater).So right now i have latest firmware PRS-650 with working russian epubs,so i let it be.On 2 different forums they called PRS+ buggy.Borodas russification seems work for my needs,so i let it be.I think Sony exe updater is either bugged for Windows 10 environment,or old boroda version 1.05 k i had on reader,prevented updating.(i managed finely exe update firmware to
https://archive.org/details/ebook-applications-firmware one from that company,just didnot like it,so i removed it.So in general,in W 10 environment other company exe updater worked,boroda update_bat worked,Sony didnot work.Must be Sony issue)