Duployan shorthand (Sloan-Duployan shorthand, Duployan stenography) is an American alphabet, written left-to-right.
“Sloan-Duployan shorthand” is not a synonym for Duployan. It is one specific mode of Duployan among many. It does not make sense to list this mode and ignore the others. There are too many to list in this introductory sentence.
Duployan is not an American alphabet. It was invented in France.
later expanded and adapted for writing English, German, Spanish, Romanian, and Chinook Jargon
This is true, but it was adapted for plenty of other languages too. Why restrict the list to these five? Unicode’s current Duployan coverage was meant to cover French, English, Romanian, Chinook Jargon, and various Salishan languages. German, Spanish, and the rest were not in scope.
“Sloan-Duployan shorthand” is not a synonym for Duployan. It is one specific mode of Duployan among many. It does not make sense to list this mode and ignore the others. There are too many to list in this introductory sentence.
Duployan is not an American alphabet. It was invented in France.
This is true, but it was adapted for plenty of other languages too. Why restrict the list to these five? Unicode’s current Duployan coverage was meant to cover French, English, Romanian, Chinook Jargon, and various Salishan languages. German, Spanish, and the rest were not in scope.