I’m going to comment and then look at what others have to say. Basically, all the conjugations and the way LingQ counts words. I have to look the same word up over and over and over and often create my own definitions using external resources (dictionaries). It drives me nuts. Of course, the better I get at the language the less I have to look up words or the better at it I get so it becomes less of an issue and over time I’ve seen the LingQ dictionary get better as users contribute to adding to the dictionary.
I can’t relate to people who choose not to learn hangul on day 1. I would say maybe develop a course teaching hangul but otherwise I don’t see the point. You could use IPA but why bother learning IPA when you can just learn hangul directly instead. And using romanization has the same problem - you have to learn how to read the romanization anyway so why not just learn hangul?
Keep in mind if you struggle to read a word you can just click/tap it and LingQ will pronounce it for you. So why would you want to us any script except hangul?
I self judge my Korean at A2 but I’ve at least looked at grammar books with intermediate grammar structures but many of them are still shaky or I don’t know them at all. I’d say I know about 1500 words as counted by a dictionary (rough guess). LingQ has my word count at 18,834.