Hi,
I'd skip Bolzano unless you're visiting the Museum of Archaeology to see the "Ice Man" exhibit, which is a must for many, including ourselves, while in the area. Bolzano would qualify as a "tourist" town.
As for Glurns/Glorenza, which is in the very scenic Vinschgau/Val Venosta, you're right on the mark with this "un-touristed" area. We stayed here and didn't meet or hear anyone else speaking English. I'm not saying English is unknown, but we didn't run into anyone from "home" or "native" English speakers. Some of the people we dealt with (hotel, restaurant, etc.) spoke some English.
Everything has a German name/Italian name and German is usually the first language spoken, as this used to be part of Austria until the aftermath of WWl. Even the town of Tirol/Tirolo, which the Austrian area is named for, is now a part of Italy in the Vinschagu/Val Venosta.
If you like quaint villages, outstanding alpine scenery and castles and many, many castles, stay in the Vinschgau/Val Venosta. We stayed here in Mals/Malles, which is very close to Glurns/Glorenza. Actually, from our room balcony we could see the walled town:
http://www.biohotel-panorama.it/bio-hotel-suedtirol/bildergalerie/
Schlanders/Silandro is a nice town to stay at also.
http://www.suedtirol.info/en/regions/val-venosta-vinschgau/schlanders-laas_ort_367
Here's how to get around:
http://www.vinschgaucard.net/en/service-info/advantage-cards/venosta-valley-card/mobilcard.html
http://www.mobilcard.info/en/mobilcard.asp
Here's a few of the castles in the area (our favorite is Churburg/Coira):
http://www.vinschgau.net/en/art-culture/places-of-interest/castles-and-mansions.html?_ga=1.172029799.513076278.1491690468
http://www.suedtirol.info/en/experience/culture-attractions/forts-castles/all-forts-and-castles?page=1&seed=&town_text=&town=®ion%5B%5D=274
http://www.schlosstirol.it/en/home/
Churburg/Coira tours were in either German or Italian. When the girl giving the tour heard my wife and I speaking English, she filled us in with the little English she knew. Very nice. Even if we didn't understand all of it, the castle was amazing, as is the armor collection.
Paul