Geofizz, my husband is dyslexic and dysgraphic with an IQ somewhere above 185. He still can't spell. He's successfully founded three tech startups, is an EE and very articulate. But he can't spell.
Agatha Christie still can't spell, and she's a best-selling author.
Some things can be remediated, some will get less difficult with maturity, but you may find that some things can't be "fixed" - only worked around.
I find each year, my son does a bit better with some spelling, but especially when he is writing reports, I'll find the same word spelled a multitude of ways within a couple of paragraphs.
At some point the progress had hit a stand-still with Wilson, so we decide to focus on other things. I refuse to make him study for spelling tests, because it is crazy-making. He can regurgitate them all the night before the test and still score a 15% on the actual test. So, instead, we use the time to do something he will retain.
Each kid is different, so what I say may not hold true for your child. It has just been my experience that the spelling isn't going to get a lot better than it is.
