Lane voltages higher than battery viltages

Well you can start by checking that the connections at coil #4 and spark plugs 3T and 4T are clean and tight.

Andrew, 

Looking at the photo of your EFIS, I see that your display is set up to look at three data points for voltage: Lane A, Lane B, and Battery.  This if contrary to what I stated in my earlier post, but still looks normal and does not seem related to your lane fault.  Keep in mind that the Lane A and Lane B are both being powered from “Alternator A” during normal operation, while the airframe power bus (and battery) is being supplied by “Alternator B”.  The amps reading of 0 indicates that the battery is neither charging or discharging, so “Alternator B” is providing all of the power your airframe is using.  

Andrew Asked:

"... One thing I am *really* curious about though, will the buds give me more info than the Dynon screen? ..."

Absolutely!  DYNON is only displaying summary information.
The BUDS Software Main complaint is that it displays so much info that it is often overwhelming.

The BUDS Level #3 software package includes display tabs for FUEL and IGNITION, INTERNAL and GSM (Generator Select Mode), and TURBO that the Level #1 BUDS does Not.

See SI-912 i-002, Pages 2 and 3, for full details.