Looks like the makings of a great thread, Roger! Good job!
On the strip chart, the state called 'Lambda = 1' doesn't necessarily mean that the ECU is driving toward stoichiometry of 14.7:1. Instead, Lambda = 1 means that the ECU is operating in closed loop. And conversely, when Lambda = 0 it means that the ECU is operating in open loop. Neither of those states confer or imply a target mixture.
Did you capture the O2 sensor voltage data as well? The GS-911 provides that information. The O2 sensor voltage data falls within the range of 0.0V to 1.0V. If Excel allows it, the O2 voltage numbers may need scaling for it to display in a readable way. Or perhaps the O2 voltage can use the Lambda zero-to-one scale.