Cool helmet BW. Sadly, the adler decal was "dug out" or uncovered and the national colors was repainted, which was not at all unusual in the period 1946-1980s in an attempt to "enhance" a helmet. Back before the 1990s, the most important thing about a helmet was its decal. Many wonderful camo helmets and overpaints were essentially vandalized and ruined by people digging out the decals and enhancing them. That's unfortunately what has happened here. The value has accordingly been cut by more than half IMHO. Look at someone working away on those decals with nail polish remover and a toothbrush as flushing 100 dollar bills down a toilet, about 5 to 15 of them at least. The liner has been mink oiled or vaselined as well, another old trick that is simply flushing more money down the loo. In this case, it's a family thing and you aren't selling it, so it's family lore, a historical artifact for your family, and has significant value to you, but not so much for anyone else. The objective value of it as a historical artifact has been significantly destroyed by lid wankery.
On the unit info, that was likely a vestige of the early history of the helmet, before such information was not put in there, during wartime, or replaced with feldpost numbers. Looks like that would be Jager Regt. 55. As for value, left alone in its original condition with camo it would have been a $1500+ helmet all day, probably a good bit more, up to $2k or better. As it is now, $1200 or so, maybe less.