The appearance of high caliber machine guns as a building for any machine gun squads made it absolutely pointless to assign stationary machine guns only to the second-tier engineering squad.
Machine gun squads are more effective in combat, a high caliber machine gun is more effective in combat, a first-tier machine gun squad can be obtained earlier than a second-tier engineering squad, and in the tech tree there are two machine gun squads that can build a high caliber machine gun, and there is only one engineering squad that can build a stationary machine gun.
In this regard, I propose making stationary machine guns available to all engineering squads. And make it available to assault squads, since many classes have a unique buildings in their specialized squads. Let the assault squad have one too.