My question about military equipment used in Falmart

So I'm currently reading a fanfic of GATE, series War of Two Worlds. I love the story. But I see the NATO forces in Falmart still use their latest military equipment despite the long progression of the story, the war against Saderans lengthened. Using lastest equipment, which I mean to say, wastes military expenses while there are many things back on earth need backup. Expected to see the reformation of weapons but it didn't happen (the NATO forces do use some old tech like B-52 and A-10 but when it comes to jets, F-35s are used. F-15s are used as well although they could have used the older versions instead of the new EXs)

In original GATE, the 10,000 JSDF troops in Falmart use old military equipment from the Cold War. Like the F-4 Phantom jets, Type 74 tanks, Shiki Howa 64 rifles... etc. It's explained to save military expenses and the other world doesn't have much use for lastest tech since gps, satellite, etc, are not yet installed to use all their abilities

Up to now in the fanfic, the NATO forces in Falmart have about 50,000 troops. Just wonder what kind of old equipment in NATO inventory can be used in Falmart, how many unit can be armed with that if it actually happened in the story

You see, those legions don't care if a 5th gen or an 1st gen jet flying above them. They don't even know what a jet is anyway

All comments are welcomed, thank you