can I even mention that it is an Amish home?
Yes.
In a FNMA world, you're not supposed to talk about people
Fannie does not, nor do federal laws prevent making factual statements about race, etc. despite the ignorant underwriting stuff that you get about religious things etc.
actions that may have a discriminatory effect or may affect the use and value of the property; or
• basing the analysis or opinion of market value (either partially or completely) on the race, color, religion, sex, handicap,
familial status, or national origin, of either the prospective owners or occupants of the property being appraised or the
present owners or occupants of the properties in the vicinity of that property.
Stating that the home was built by a community who does not believe in electricity in their houses is a statement of fact. If you have one sale, that means adjusting non-Amish owned homes to get there. OR, go to another area where there are other Amish. E. Ohio, PA, MO, NE Okla, etc. We have quite a few families here but they are generally working on farms owned by non-Amish farmers in houses that are provided by their employer. Many have computers since these poultry farms are tied to a computer which alerts them of conditions in the poultry barns. And most carry cell phones. I've seen them pull over to use a cell phone.
Each community is run differently. Some have electricity, some do not. Some drive buggy and horse, some tractors, some even drive a vehicle, especially if it is their employers but that is rare. Our local ones are very fond of ATVs. Some allow women to drive tractors, some frown on it. The church is rarely a building, but more likely meet in someone's house. Old Order Mennonites are similar.
Your buyer pool is limited to others of like faith or folks willing to retrofit the house with electricity and generally, plumbing...So does it have running water and a bathroom?