traceroute on any device will always use the corresponding route for the target. If there is no statc route for the target it will use the default route. If you have 4 WAN then you either use sd-wan (then the sd-wan decides which wan is used accoarding to the balancing algorithm you chose) or you have to have foour default routes with diffrent priority or distance and then those are used top down by prop/sdistance.
I don't think you can tell traceroute to use a specific interface.
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