Some people have a harder time getting used to change than others, I believe when more lines are added the character will be fleshed out more and you'll have a better idea what Valve is shooting for, you just need to be careful how you take things like tone and line delivery. In my opinion Crystal Maiden's tone fits her character just fine, she's supposed to appear young and naive because she's just recently begun to fight. Lina on the other hand is supposed to act as a foil to this, Maiden has been essentially in apprenticeship for the last few years and sheltered while Lina has been essentially on her own fighting and learning, and her lines reflect this with a much harsher tone.