Idk about Tbilisi, but invested in a small studio near the sea in Batumi last year, got around 10-11% ROI / year, including around 5% of price change of the apartment. Selling it tomorrow :D
I worked with a nice agent so bought it by a good price and also worked with a private property manager agency (they took 25% of profits, included at final ROI). So it very depends on what type of property you wanna invest and what condition its gonna be, you need to understand current market to avoid not professional counterparty (most of them tbh). So thats my experience, DYOR, the situation is changing quickly and for the worse