Well the Pattern 14 & M1917 Enfield were never really front line rifles. The design was from WW1 so they were really only given to rear line or home guard units. Maybe sometimes (when supplies of main battle rifles were low) were they given to front line troops, but I haven't really seen anything saying that they were. They were also mainly only used in the early part of the war ('40-'43ish).
It's important to note that they look the same and were both made in the same factories in the United States BUT the P14 was chambered in .303 (British standard ammunition) and the M1917 Enfield was chambered in .30-06 (American standard ammunition). That's why you don't see much swapping between the two.
Going off of Wikipedia, we seem to have them in the right roles in-game; the P14 (being known as a more accurate gun and made into a Sniper Rifle in WW1) is mainly used as a sniper rifle in early war maps.
The M1917 was really only issued to artillerymen/ rear line troops early in the war (so the ammo kit and mine kit in 1943 Africa). Unfortunately, I can't think of many other places to add them.
Wikipedia (which isn't the most complete source) also says that;
Post Dunkirk and with the great loss of arms that the British forces endured in 1940 the No3Mk1 (Pattern 14) stock suddenly became a valued resource.
So maybe the British used them a bit more in secondary campaigns like Greece after the fall of France? Would have to do more research on that tho and I don't think they were put into front line use.
About the M1917;
Others were supplied to the Nationalist Chinese forces... [and] to Filipino soldiers under the Philippine Army and Constabulary units and the local guerrilla forces and to the Free French Army, which can occasionally be seen in wartime photographs.
So CMP could possibly use the M1917 in more roles on their Invasion of the Philippines map.
At the end of the day it was just an outdated rifle and we don't have enough early war maps atm to add it.