"Perhaps that is not cheese."
Translation:To možná sýr není.
"Možna není to sýr" could be valid? Word order in Czech is (in most cases, not all) not as strict as in other languages...
In this case, the word order is wrong. Another acceptable order would be "možná to není sýr", but you generally have to follow SVO order, that is Subject-Verb-Object, here Subject = "to", Verb = "není", O = "sýr".
Keep in mind, that this is more of a guideline than a rule, and works generally with nouns being objects. Pronouns have very weird rules to them. For example: "Máma to vaří" = Mom is cooking it "Máma vaří rýži" = Mom is cooking rice