Whether or not a center lower LATCH installation is allowed in your Caliber depends on the child restraint type and the child restraint's manufacturer. According to the LATCH manual, you're allowed to install in the center rear using the Caliber's innermost lower LATCH anchors in the vehicle seat crease (bight) from each outboard (side) position if the child restraint has flexible LATCH (a flexible, webbed LATCH connector strap or straps), and if the child restraint manufacturer also allows borrowing of the outboard lower LATCH anchors.
A child restraint with rigid LATCH, such as the Baby Trend Latch Loc infant seat, for example, which has solid LATCH connector bars rather than a flexible LATCH connector strap or straps, cannot be installed with LATCH in the center in the Caliber. Some child restraint manufacturers do not allow borrowing outboard lower LATCH anchors even with flexible LATCH child restraints. Your infant seat's manual should indicate if borrowing is allowed, and sometimes this will be specified in the manual in terms of an allowed spacing between the lower anchors. You can also post back with your infant seat's manufacturer and model name for us to double check for you about borrowing outboard anchors.
On a related note, a lower LATCH anchor installation isn't considered safer than a seatbelt installation, or vice versa, provided that you can achieve a proper installation with less than 1 inch of movement at the child restraint's belt path using an approved installation method for the particular vehicle seating position. The LATCH system was originally conceived with the intention of simplifying installations in theory, but in practice that's not always the case.
Hope this rather long-winded answer helps you out.