Mate just chill. UKF has all of these things and it is fine Why shouldn't ost have them? Oh, and I hope You will show me how to use 4 men grens. Pleas feel free to demonstrate. You could upload a replay.
People reason to bitch about werhmacht infantry performance is because midrange is not their domain with the possible exception of spamming G43's.
If you aren't any good to set up thing into account for that(for example recon, barbed wire, anything that hinders/compromises advancing allied infantry), you will always fight at a disadvantage against nummerically superior squads that have to get close to grens to win the day without excessive losses or a retreat.
That they are individually great tools at long range is seldom considered though(apparently). Best get 5men mid range grens to compensate for their weakness. AKA disregarding balance.
You already have great team weapons that can cover this, most notably the MG42.
So no, Ostheer does not need 5men grens nondoctrinally(in my humble opinion,
And i dare say the balance team feels the same). If you say that the british have the better end of the stick due to bolster, look at the British instead of Ostheer. I mean, having bolster take up a weapon slot as an upgrade(much like bolster for Cons at T3/4) would be a fair tradeoff imo.