My DH's range of vegetables he will eat is very similar to yours and he manages as a vegetarian!
He'll eat all the things on your "ok" list except sweetcorn which is "of the devil" apparently, and from your "terrible" list he's happy with courgette, and will accept occasional small quantities of cucumber, broccoli and tomatoes but will agree with you on all the rest. Left to his own devices he wouldn't have a range wider than peppers onions and mushrooms but expands from this for my sake.
Given that your tastes are broadly similar to his, you may find a few others that he'll tolerate worth a try:
We regularly have either savoy or cavolo nero cabbage finely shredded and steamed and combined with sautéed leeks in mashed potatoes for a delicious colcannon
Aubergines are great if cooked well - there are many people put off from aubergine by bad cooking so they are worth trying done in different ways.
What do you think of mangetout? Asparagus?
You say you'll tolerate lettuce but perhaps try some different flavours of leaf like rocket or watercress?
Given that you like carrots and red onion, try making a coleslaw with these plus red cabbage?
I don't think your range is too bad but it would be a bit dull trying to get your "five a day" with a choice of only 6 types of vegetables so if you could get your range up to 10 that would be a bit better. You maximise the health benefits of eating vegetables by "eating a rainbow" because different colours are a general indication of different trace nutrients so focus on adding things that are different shades to items you already eat.