SYS_RESET_N is reset for PMIC and SoC, which triggered by hardware (e.g. reset button, power on button). MAINSWRST is reset for SoC only, which triggered by software. (e.g. system reboot)
What problem do you have with “MAINSWRST” condition?
You can refer to the following message from Product Design Guide: System Reset: Connected to NRST_IO of PMIC. Bidirectional reset driven from PMIC to carrier board for devices requiring full system reset. Can also be driven from carrier board to module to initiate full system reset (including PMIC) (i.e. From RESET button). 1kΩ pull-up to 1.8V is present on the module.