Dealing with Languages

I addressed your endorsement of the take of TSE p.41 on Veneto in:

This endorsement of yours is quite clear from "My placement is consistent with this, while your placement goes the opposite way." Don't try to wiggle out of it. Actually, though, such issues need to be resolved by checking the 13th century text instances we have: don't make 'placements' unless you have done so.

When treating medieval languages, vernaculars and dialects, you have problems that you address yourself as:

, and as

I don't know which languages besides English you actually can handle, when confronted with a 13th century text. Just tinkering with English wiki articles classifying languages and vernaculars doesn't get you anywhere consistent, if you cannot verify whether a given instance fulfills the classification criteria: especially, as wiki linguistic classification for long-living languages typically addresses the present state. Also, linguistic classifications of Romance languages address their development from Latin, and hence require decent understanding of Latin language and grammar to make sense of.

In your case, you might drop referring to refined linguistics and go back to the - often quite accessible and even translated - 13th century history and sources. Here wikipedia and wikisource are your friends.
You wish to propose game rules for communication after all. With Italian, Dante's partisan fragment De vulgari eloquentia is far more helpful to you than contemporary linguistic classifications: he addresses his own erudite contemporaries, who knew full well the languages and vernaculars around them. And if Snorri Sturluson in the Heimskringla implies, that there is a single Norse language between Iceland and Sweden, you better believe it for the 13th century.
If you can handle just a little German and have 10 EUR to spare, get Joachim Heinzle: Das Mittelalter in Daten, half of which just lists a choice of literature of each given narrow time period (like 1221-1225), sorted by cultures. It doesn't address Byzantine, Arab and Jewish literatures, though.

Because your post did not refer to it.

I steer clear of your tables: I myself - despite being able to at least read those languages needed to study history of the middle ages between Scotland and Sicily (Latin, French, English, German and Italian) - would need a lot more than "dozens of hours" to make them worthwhile.

Cheers