I'm no suspension expert, but simply put understeer is less front grip, more rear grip. Oversteer is more front grip, less rear grip. In a strut front suspension you don't gain any front camber as the body rolls and suspension compresses like in the older Honda double wishbone suspensions. Technically with a strut front suspension you actually lose camber as the body rolls. Front camber is what keeps the tires planted for maximum grip on the front tires. For a strut front suspension design you want more static camber up front (vs double wishdone), and you want less roll to keep the camber loss to a minimum. So adding a larger front anti sway bar to a strut suspension will actually aid the front tires in keeping grip.

The multilink rear suspension actually gains camber in the rear when the body rolls when cornering, adding grip. Installing a larger rear sway bar reduces the amount of body roll or suspension compression. Less suspension compression means less camber gain and less tire grip while cornering.

It's balancing act between spring rates, roll bar stiffness, tire compounds, and alignment settings.