Is there any language with --cut-off-date working?

How do make the -`-cut-off-date` option work? I'm working with Middle English, the period before the end of the 13th century. There are graphemes and pronunciations from the beginning of Middle English. it is ok, but I can't filter them. I didn't see any date in ,tsv files (concerning English) either. It would be helpful to know which data sources were used.

Start at the --cut-off-date command-line entry point and inspect the English .tsv data files and their source references. Document how date filtering is expected to work for Middle English, identify whether the available data contains usable dates, and list the sources used.

Written by the indexing model from the issue text.