I'd never come across this usage either (19th-century piano not my 'forte'), so how best should such possibly misunderstood usage be conveyed to the reader?
Similarly, Pergolesi alternates between 'dolce' and 'forte' instructions, which suggests that the former is more of a dynamic than a mode of expression. (Piano is never used.)
So: where does the balance lie between faithful transcription and use of terms with modern accepted definitions? (On the assumption that the readership may not all be musicologists.
