If it's an international brand ('samsung galaxy') then usually in english but sometimes in cyrillic (for example all car brands are always in cyrillic, McDonalds, Pepsi-cola would be also in cyrillic), otherwise ('bed', 'chair') in cyrillic 100% of time.
There's no such thing as "russian latin alphabet". It's called transliteration and is used when it is absolutely impossible to use cyrillic, for example when some device does not support cyrillic charset or in function names/in comments in programming code. Nobody uses translit when does search online or in everyday life, it's usage in internets has been in steep decline since unicode was introduced everywhere.
So, if you're going to go after keywords, I'd suggest cyrillic first. If you're going to promote some obscure electronic device/brand which is not on everyone's lips - go for the brand in english + words such as "buy" or "info" in cyrillic.
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