Is it safe to ignore the lm-sensors voltage alarms?

The limits aren't configured correctly, they're probably defaults or from some other board. For example:

+3.3V: +3.38 V (min = +0.82 V, max = +0.59 V)

That looks reasonable for a 3.3V supply, but the limits are completely out, and the max is lower than the min!

temp2 looks a bit worrying, but that may also be a misconfigured sensor.

Voltages are rarely reported by drivers correctly, because a scaling factor needs to be applied to the limited range of the internal sensors.

See this page for a description and tutorial of how to fix the scaling factors for your particular system setup:

http://www.lm-sensors.org/wiki/VoltageLabelsAndScaling

Once you know which sensors are reporting which voltages, and the numbers are scaled correctly, you can setup or max and min values appropriately. The page above gives an example of this.