The answer to this question is probably 'yes', but we'd need more context to know for sure.
What I do know ( and you probably know it, too) is that Russian speakers tend to use the English word 'variant' wrongly. A typical Russian speaker's mistake is to use 'variant' to refer to the options A, B and C in a multiple choice test, where only one of the options is possible.
To use 'variant' correctly, you need to be referring to a slightly different version of something known and standard. A variant differs from a standard version usually only in a few aspects. For example, a motor manufacturer might produce a variant model of a car, which is basically the same car but with a few minor features which make it different. Or the pathogens of a certain disease may mutate to produce a variant which is a slightly different strain of the same disease. One way of looking at American English and British English is that they are both variants of the English language.
So, back to your original question. If by 'translation variants' you mean two possible ways that a phrase can be translated, then the answer is 'Yes, it's unnatural. 'Variant' is the wrong word and 'option' is the right one'.