Right, 104 symbols would be the minimum if you do need to read/write cursive.
However, I don't agree with your point about typeset text. You're right that the styles differ, but if you have learned one style, and know the language of the text, you will not need any significant amount of time to read a different style of typesetting.
Russian of course normally uses the Cyrillic alphabet, not the Latin one, so obviously you do have to learn a whole new set of symbols to understand it even if you can read Latin symbols. And of course French uses slightly more letters/letter forms than English, with the sedile and four accents (egu, grave, circonflex, and very rare treme).
Lots of accents when using Cyrillic to write non-Russian text.
I didn’t mean the typesetting differences made reading a different language in any way hard, merely pointing out that there are lots of different aspects to text in different languages even when the alphabets are basically the same.
However, I don't agree with your point about typeset text. You're right that the styles differ, but if you have learned one style, and know the language of the text, you will not need any significant amount of time to read a different style of typesetting.
Russian of course normally uses the Cyrillic alphabet, not the Latin one, so obviously you do have to learn a whole new set of symbols to understand it even if you can read Latin symbols. And of course French uses slightly more letters/letter forms than English, with the sedile and four accents (egu, grave, circonflex, and very rare treme).