We recently updated our eventlogging to look at click events rather than just visitPage and we now have the original logging and the new logging but with very different results between the two.
This ticket is to investigate what we're logging, what changed and what might be the best to update it to in order to distinguish interwiki clicks correctly.
A suggestion from @EBernhardson:
the three extra parameter values that we have: we only need these on SERP events. they're actually redundant on the click events. this means that for click events, we can use the extra params field to have that interwiki boolean flag.
This work to be done is effectively blocking a lot of testing that we want to do on the Search team and specifically this: https://phabricator.wikimedia.org/T136017