"Ti jsou moji."

Translation: Those are mine.

[va-diim]

Would to jsou moji be acceptable?

[kacenka9]

Not really. You would need to say what TO are. For example TO JSOU MOJI PSI. Without "psi" or other noun the sentence does not make much sense.

[Marko195]

No, it does not be acceptable, because it is a different sentence as well as a meaning.

This has the same way of use in Czech and my Serbian.

In Serbian:

Those [dogs] are mine = Ti [psi] su moji

They are mine = To su moji

It is used knowing the context.

[Foxxa]

Why "These are mine" isn't accepted?

[VladaFu]

Tito jsou moji.

[Pollyhs]

ty jsou moje? Is this correct?

[VladaFu]

yes

[Ale632702]

why is not accepted "they are mine"?

[VladaFu]

Ti is not just they (=oni), it is a demonstrative pronoun meaning those.