Despite other flaws, the biggest (or maybe second biggest) issue I had with Solo was Lando's backstory.
See, I grew up reading some very old, very obscure EU books about Lando. In that series Lando was an expert card player but a poor pilot, and a lot is made of how he won the Millennium Falcon in a game of Sabacc but has no idea how to fly it. The movie reversed this, making him a card cheat.
I'm probably they only person in the world who cares.
But maybe new series, if it ever comes out, will be about Lando and his adventures with Vuffi Raa?
I agree, his character felt a bit 2D in Solo. If they had gone with Lando's backstory from the book, it would've added a lot to his character. Not knowing how to pilot is a fantastic character flaw. It adds new motivations to move the story forward and makes Lando more relatable. Being a bad card player is an ok flaw, but it's made null by being good at cheating. He's solved his own problem, so nothing is added to his character except a little flavor.
Being the third member of a trio of pilots to ever have survived torp'ing a death star AND a notably bad pilot is certainly a major character Arc growth. Also adds a bit of flavor to the "not a scratch" gag from rotj.
You may be interested in Expounded Universe, the podcast from System Mastery where they discuss EU novels. That’s the first episode on the Mindharp of Sharu.