Who made the script? Was it Isaac? Ben? Is the diacritic mark (that phrasing surely is spoilerless) something you guys canonically have, and is it something Team Dragonsteel would be willing to show the fans?
Isaac is in charge of the scripts of Stormlight. I give him words of description, and he makes the actual pictures--and does a wonderful job. I've told him he can explain the methodology.
One thing to keep in mind is that we can't often do 100% in-world text for things like this, as (unlike Tolkien) I haven't fabricated the entire language. I've got bits and chunks, but not nearly enough to write in-world with full linguistics. So it's often "interpreted" for the audiences by writing it out in an Earth language, then writing it out using the Women's Script.
This means you're not getting it exactly as it would appear in-world, if it were a real language. It's an approximation. (At least for now.)
Yes, I totally get that part. Like the "steel alphabet", when we see it it's mostly just being used as a code for English.
I don't know if you recall something like this off the top of your head, but is there an actual H in the script, or is that sound only produced by way of the diacritic mark? Like, the name Tarah. Is she T-A-R-A-T(marked), or honestly just T-A-R-A-H natively?
The "H" is a mark, as you suspect. You put it on another letter, transforming it into an "H" sound, but otherwise letting the word look symmetrical.