I. e., can a form field in PDF exported from ID have sideways text, when being filled?
Property 'rotationAngle' rotates only bounding box, but text inside it remains horizontal:
var someDoc = app.documents.add();
var someform= someDoc.pages[-1].textBoxes.add();
someform.geometricBounds = [20, 0, 30, 100];
someform.rotationAngle = 90;
While Acrobat is definitely capable of rendering sideways form fields (Tools/Prepare form and then Properties/General/Orientation)