When you press X, it INSTANTLY skips to the end of the current textbox. Same with holding C, it doesn't go through each of the letters but instead progresses past through each textbox quickly. So, essentially, language setting doesn't make a difference. It MIGHT make a difference on the "Susie joined the team!" textbox and the textbox after that one ("Susie followed at a distance as to not be associated!") but it probably doesn't due to the fanfare.
NEW UPDATE: I have managed to use the trick to get to Central Alwa after the boss. By using this strategy, it might even be possible to skip the boss! I also skipped most of the Sea Monk dungeon by using a combination of block jump and the bubble to get to the Sea Monk early. You might know this area where you see a boss door you can't get to on the top right. You stand on a ledge on the bottom left. I SKIPPED the wall and got to the high up boss door. Using these tricks, it may be possible to fight the bosses VERY out-of-order!
I'm not sure if people have found this already. This is my first playthrough, and I found this. I haven't gotten the huge orb upgrade yet in the first dungeon, but there is an area before the boss where there is a bird statue under a wall. If you place a block keeping the bird from shooting fire in front of it, then try jumping off it, you'll get nowhere. However, if you stand on the block and press left, you can then jump. RIGHT BEFORE you hit the height of your jump, place a block. Hold left until you see Zoe's walking animation. Once you see it, you can jump and skip the wall entirely!