It is only pronounced “froy-lyne” if you spell it correctly as fräulein. Frau (without the umlaut) is pronounced to rhyme with brow in eyebrow.
How do we really know how archaic words were pronounced prior to the advent of recording technology? However, it is probably safe to say that since the “s” was dropped from “disme” it was probably a reflection of the actual pronunciation. Hard to say though if the “i” was pronounced ee or ai.
Exactly. Look at how many times and ways f and ff are used in written statements of old. If you were not aware of the many different uses it would be difficult to understand the documents.
I'd render it as "foycht-vonger", but the "ch" sound doesn't match anything in English (just as our "th" doesn't match anything in German). If you can imitate the sound of the vacuum-thingy your dentist uses to suck water out of your mouth, you've got it. I understand that a German Southern accent would pronounce it "foysht-vonger", but I've never been there.
I spent half the morning looking for the magazine article that I remembered that discussed the pronunciation of "disme" but I couldn't find it (checked John Reich Society journals, The Numismatist, and even Greysheet articles). So I went to online pronunciation guides and three out of four said said "dime", one said "dis-meh", and one gave both English French pronunciations, link below: https://forvo.com/word/disme/ English was "dime" and French was kinda "diz-meh" with that typically French nasality. In my mind, the 1792 half disme is quintessentially American so all foreign pronunciations should be ignored. I think the "proper" way to say it is "dime" but please understand that I am generally a free-thinker when it comes to American grammar, usage, and pronunciation in non-formal, non-business, and non-academic settings. So say it anyway you like and I won't mind.