Yes, the L model saw service in Europe. I don't think in the numbers that saw service in the Pacific though. Nor do I know what models the Free French and the Italian Co-Belligerent Air Force flew but I think those were probably a mix of G, H and J models but they might have received L models in mid-'44 or maybe even retro-fitted late model J's.
In the later stages of the Euro war, think from mid-44 and on, the P-38's primary role was starting to grow into that of an attack plane. It was no longer one of the primary air superiority fighters of the USAAF, P-47Ds and P-51Ds had taken up that role. Even though the L model and retro-fitted late model J's fixed pretty much all the problems that plagued the older models. That's not to say that the P-38 in the later stages of the war weren't tasked with local air superiority or air defense missions, it just wasn't their #1 job anymore.
The L model also saw life in forms of different variants like the F-5 recce version and the P-38L "Droop snoot" that was used on pathfinder bombing missions.
P-38L "Droop snoot" pathfinder
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