Would hyoscyamine be used to treat menstrual cramps and bloating?

Yes it can. It might not help 100% for menstrual cramps (NSAIDS might help more) but it will help with abdominal discomfort, bloating.

Hyoscyamine produces many effects in the body, including relief from muscle spasms.

Hyoscyamine also reduces the fluid secretions of many organs and glands in the body, such as the stomach, pancreas, lungs, saliva glands, sweat glands, and nasal passages.

Hyoscyamine is used to treat many different stomach and intestinal disorders, including peptic ulcer and irritable bowel syndrome. It is also used to control muscle spasms in the bladder, kidneys, or digestive tract, and to reduce stomach acid. Hyoscyamine is sometimes used to reduce tremors and rigid muscles in people with symptoms of Parkinson's disease.

Hyoscyamine is also used as a drying agent to control excessive salivation, runny nose, or excessive sweating.

https://www.drugs.com/mtm/hyoscyamine.html