I’m going to look into some workflow options that will (among others) address your feedback, not sure how long that will take though.
Once you have completed a target, by the way, you can still ‘go back’ to it from the menu. There’s an option to visit the most recently finished item, if it exists. When you do, you get a full-screen info dump and you can go and edit your notes and synonyms from there. Doesn’t work for partially completed targets (meaning done but reading not done or vice versa), but it’s something.
And yes, your notes and synonyms are integrated in the subject info dump: your meaning notes and meaning synonyms are shown with the meaning-related information, and your reading notes are shown with the reading-related information. The only thing is that those two chunks of information are currently clumped together in a single view, and you’re not the only one who’d like to see that split up