yeah the rythm will be determined trough the variations of - and number characters in a tab.
It is almost nevery really good.
I can even provide my program if the community has some use for it. It isnt perfect, and not all of the tabs are well made, but it often can provide for short melodies an idea about how to play them.
In general it is two programs, one for making a midi out of a tab, and the other one converts a tab from an instrument with a tuning into another instrument with a different tuning.
I recommend to use both programs, because you get a quick preview about how the tab sounds, and therefore if it is properly translated.
Also the converter tool doesn't support symbols like hammerons or pullofs, because there is simply no good way to implement this in my logic.