switching power supply pcb layout
Via placement should be of least concern here. The biggest  problem in your layout/placement is that high-current loops are forced across planes (top and ground) via extra vias. Look again at the manufacturer's suggested layout: all high-spikes loops are closed into the same ground pad, top layer, and under the chip. All are tightly localized around the control switcher. In your design, the current must pass between layers (and along the signal ground), and inductance of vias will likely increase ringing, and EMI from your layout will be horrible. Please be less inventive and try to follow the suggested layout as close as possible, including suggested BOM. It will save you a lot of troubles.