Regardless of weapon teams, Rifle Nades are just a really poorly designed mechanic. They don't clear garrisons properly, which is what they're supposed to do, instead they result in gimmicky, effortless squad wipes.
Firing a Rifle nade over a shot blocker that you literally can not see coming and have no time to dodge because it's instant detonate resulting in a squad wipe is just silly. It also makes no sense how they detonate instantly, combined with the fact they have the best animation that can be very hard to spot compared to other grenade animations. It also breaks late game and makes LMG Grens far stronger than what they should be, because it makes other long range LMG unable to remain static for fear of being instawiped. This encourages blobbing because you can't risk fighting on multiple fronts against Rifle Nades.
Giving Grenadiers regular grenades like Volks or Fusileers would be a great chance to not only increase the viability of allied support teams, but also just to decrease the skilless "free" squad wipes and result in more tactical play. It would also help Ost clearing garrisons which is something they lack.
It would be extremely unbalanced for Grens do have regular grenades. Why? Because grens are long range focused. They are countered by closing to close range with them and duking it out were they have the least DPS on their LMG and take the most damage from you. They also can't use their rifle grenade in CQC.
Now if they had a regular potato masher? You could just throw a grenade in the path your enemy is rushing you from to wipe them. I don't think the solution to rifle nades over preforming is to make Ostheers basic infantry unit good at every range and situation they might encounter.