I am having the same issues as pinkbroker (I am fully updated to latest iOS, etc.). You’re correct that some of the problems are general to Scribble across all apps (e.g., poor capitalization). But the most frustrating thing for me on Agenda is that the cursor will randomly “jump” from inside the note to the header line, for reasons I can’t explain. When this happens it deletes out the note title with whatever I was scribbling at that moment.
This kind of behavior is unique to Agenda. On Things, Bear, etc., I put the pencil down at the location where I want the text to go and start scribbling — and the converted text gets inserted at that location.
My current workaround is to open the drawing attachment and write by hand there during a meeting or brainstorm when I want to jot stuff down without typing, and then go back to type up permanent notes that I want to be searchable. That’s okay, but a time waster compared to other notetaking apps. In Things or Bear, I can scribble directly in the note, and then my review is just cleaning up capitalization and spelling errors. Alternatively, in Goodnotes I can just write by hand and my handwriting is fully searchable. I would like to convert from Goodnotes to Agenda for the date functionality, but I really prefer note-taking by hand so it’s a constant tradeoff for me.