I was teaching a friend how to make ravioli (yes, really) from the class I took while over in Italy. I bring my scale to measure the dough and the first thing she does is use the scale to get the right measurements and then, scrapes the contents into an imperial measuring cup. Worse, she was totally pissed when the semolina was not a perfect match to the 00 flour (mass and all that).
She is a tried and true American. She just wants to whip out her 1 cup without measuring weight and can’t fathom why the dough just “wasn’t like I taught her”.
By the way, the super secret Italian recipe is this:
Ingredients per 2 people (spaghetti or tagliatelle)
100 grams total of:
50% white superfine flour
50% semolina
Add 1 egg per 100 grams of flour
For ravioli, you want more superfine (00) flour so the pasta sticks together better. So like above, 100 grams total of:
60% superfine flour
40% semolina
To be honest, ain't nobody using that measurement unless you are using commercial canned shelled eggs for speed. And even then you are probably just going to open the can and dump the whole thing. But it does show that the system is complete.
Rare indeed would be the home cooks/bakers that used that.
What most people miss about weight vs volumetric measurement when cooking is that it's all about ratios. And if you had been paying attention in math class, you would know that ratios are unit less. Which means as long as you keep the proper ratio between the ingredients, it matters not one whit on how you measure them. You can weight, you can use cups or spoons or handfuls and pinches to achieve the correct ratio. You even demonstrate this by stating that the ratio of flour to semolina is 1:1 or 3:2 depending on the end use. And one extra large egg, (about 55 grams or 2oz), should make for a decent conversion.
But before you change units of measure, you need to be sure that the changes still hold to with the tolerances of the recipe. Something most people can't do very well - much like your friend.
And never forget - the true masters of fresh pasta making at home are all those little old Italian Grandmothers. And they are probably just eyballing it all anyway.
Which means as long as you keep the proper ratio between the ingredients, it matters not one whit on how you measure them. You can weight, you can use cups or spoons or handfuls and pinches to achieve the correct ratio.
The problem with converting a 1:1 ratio of ingredients measured by weight and a 1:1 ratio of ingredients measured by volume is density. Two different kinds of flour may pack differently and thus have different densities enough to effect the consistency of the dough. And with something like flour, a cup of sifted flour is less wheat and more air than a cup of scooped flour.
It's all about the ratio. The density does not matter as much as you seem to think. Plus there is a tolerance built in. Just think, you so carefully measure everything out with weight (did you get the weight exact?). Then you randomly toss a bunch of bench flour down when you kneed the dough. You have literally no clue as to how much weight of flour/semolina the dough picked up. So it really doesn't matter as much as you might think. Now your scale does make it easier for you. And that's fine, I have a kitchen scale and use it regularly myself. But I understand it doesn't matter as much as you seem to feel it does.
And again, those Italian Grandmothers are just eyeballin' everything anyway.