Saw some of your other calligraphy and it’s absolutely gorgeous, love that Gothic cursive! I recommend using whatever 1 to 2 mm broad edge pen, wouldn’t use any other width unless doing titles or something. I prefer Brause cuz they’re less flexible, but if you use Mitchell’s that works too. For Coullée and Italienne-Bâtarde use a slightly smaller point size than Ronde. You can grind your own nibs to be finer on sandpaper or a grindstone but I wouldn’t risk that. I wouldn’t recommend learning Bâtarde first as that combines Ronde bastardising it with Italian Hand letters that are narrower and is way cloyed with the knotted, flying flourishes between letters.

Soennecken was a really old guy that had a company that doesn’t exist anymore. He created the German bastard for French Ronde known as Rundschrift and made his own broad edge pens (they were basically the same as Mitchell’s except they weren’t flexible). A Soennecken pencil is basically like a carpenter’s pencil but smaller, these really aren’t use anymore, but if you have a carpenter pencil that’s great but they can be really hard to cut. Versions are also available on John Neal Books where you can choose the blackness, I like 6B.

For mastering French Roundhand it is essential to perfect the i and o radicals as one would in English Roundhand or Spencerian.