Q.Hyacinth beans
I inherited a small bag of what is marked, “Hyacinth bean” dated 1999. Are these too old to grow? Is there anything I can do to encourage growth?

There is a good chance that your seeds are quite viable.
Heirloom seeds, or seeds passed down are wonderful to garden with.
https://www.gardeningknowhow.com/ornamental/vines/hyacinth-bean/purple-hyacinth-bean-care.htm
Here are some articles to help you.
https://www.gardeningknowhow.com/edible/vegetables/vgen/heirloom-vegetables.htm