The M22 in the American tech tree currently does not reflect the actual service that the M22 saw during World War II. Despite being the country that produced the tank not a single M22 would see combat with the Americans, and this makes sense as the Americans did not want it to begin with.
The design of the Locust started with a request from the British War Office to US Army Ordinance for a purpose built gliderborne tank. The army gave the task of creating that tank to Marmon Herrington, who (after a lot of modifications and issues) would deliver 830 tanks. 230 of these would be sent to Britain for use with airborne troops.
The British performed modifications to their tanks to better suit their needs. a pair of smoke grenade launchers were added to the turrets, but more importantly for this proposal a Littlejohn Adapter was added to some amount of tanks. The Littlejohn Adapter worked on the Squeeze-bore principal to increase the penetration of the gun, by compressing the soft steel outer layer of a tungsten carbide cored round in order to prevent gases from escaping past the round. In testing this allowed the 37mm to penetrate 100mm of flat armor at 400 yards, and 80 at 30 degrees and the same range. Use of the adaptor removed the ability to use HE shells, and the modifications to the 37mm cannon to fit the adaptor shortened the barrel to the point that without the adaptor fitted the gun was useless.
The Locust would see exactly 1 combat action that was by all accounts a total cluster, during Operation Varsity in 1945. During this action 8 Locusts were used. one destroyed the glider it was in midflight, one was destroyed on landing, one broke down trying to tow a jeep, and one was destroyed by a german armored vehicle. The remaining 4 did support american infantry, with two that were damaged and immobile covering the two remaining healthy tanks. After this action, a photo was taken of a Locust, and I believe that I see a littlejohn adaptor attached.
In all, I think that a M22+ with improved penetration, smoke, and spotting would be a absolute riot to play. Sources and stats are below