Memorex, the movement pause you're noticing is a new song starting. When you change maps, your characters finish whatever movement instruction the "door" (called a door even if you walked up a dirt path to change areas, etc.) you entered through gave, then the automatic event for the new map activates. If the automatic event plays a different song than what's already playing, the current song stops and a new song starts. In vanilla, stopping a song to start a new song locks up the game during both the old song fading out and the new song loading. With Turbo, Audio\Async_Music_Crossfade removes the lock up during the old song fading, but loading the new song still causes a framerate hiccup (usually). This means you get to move for a moment while the previous song fades out, unlike vanilla where after a map change you just can't move at all until the new song has loaded. Ultimately, I'd like to improve SoM's song loader to not have to pause the game as noticeably; I've tried before and failed, but still expect to figure something out someday. While you might be noticing it more clearly with Turbo (again, Async_Music_Crossfade specifically) since you get to move for a moment before the pause, you actually lose less time than in vanilla.
Eventually I want to improve the Goblin Village so you don't always get teleported to the totem pole when you enter (from either west or east); hopefully if you entered where you exit, people would be less confused about how to leave. There are very very few unused doors, so using two just for that tiny map feels like a waste; I also would like to make a combat version of the map to use (and one that is affected by time of day), so as to feel like those doors are being put to good use. Pretty complicated work though and haven't found the time to work on that.
The signpost collision is probably unfixable. They use a specialized tile collision option to trigger their events (to show text), and have a lot of caveats to work correctly, one of which is their odd horizontal collision. The tile for the signpost message event doesn't let you enter or leave that tile horizontally. I suspect the original developers wanted the signs to only be "read" if you were facing upward, specifically looking at them, and this was how they accomplished it.
hmsong, like ManaRedux said, we only just noticed the Undine cave message issue as well. It's been changed.
ManaRedux covered your questions regarding Seal and Luka's titles.
For Jema turning to face the boy, that's the same timing/behavior as vanilla. Looking at vanilla, I think the intent was Jema says a short line addressing the boy, THEN they turn to face each other to acknowledge the shift in conversation. Like, Jema says it before turning his attention away from Luka. In Reborn, this line became much longer, so the delay before they face each other is more awkward, but it does still occur at the same point in the conversation.
I could probably change it so that Jema turns to face the boy as he says that line, and the wait after it will only turn the boy as a reaction. That should make the interaction feel more natural. We tried to keep event actions/animations the same as vanilla, since they're also the same as the original Japanese. This is trivial for me to change in Reborn, but whether we do is ManaRedux's call (not trying to put you on the spot, just that this sort of design choice is up to you).
Some outright bugs in events HAVE been fixed in Reborn, just to make inserting the new text as painless as possible if nothing else.