Yes, the 'shadow' picture is from the incident battery.
The thermocouple I pictured is purely a generic device whose mounting tab looks like something that could have been bolted to that cell linking strap.
I really don't think this sensor had anything whatsoever to do with cell monitoring or even thermal runaway. I think it is purely something to record the ambient temperature of the battery to see that it is remaining within the -X to +Y degrees specified by Yuasa.
