Sappers snare range is 15. Grenadiers have 18, and the +7% range bulletin increases that to 19.
Grens have a higher range because they are a (defensive) 4 men squad that cost 30mp per model to reinforce after having to expose themselves to enemy vehicles, and because Ostheer doesn't have a stock light AT vehicle to deal with Allied LVs.
I understand your logic, especially with how nuts the T70 is however...
What I would argue is if WASP range was nerfed to let Faust's become a viable counter, hard counter even. Then why do OKW not get the same range bonus?
222 can hard counter the wasp before OKW puma or luch even begin production. So the LV argument you use would be moot here.
I think Faust's and US AT nade should all be standardized, if one or two vehicles (T70, AAHT, valentine) are causing issues then they should probably be nerfed.