I haven't forgotten you either, @Mr Poltroon, I've just been ignoring you since you asked about stuff that was harder to answer.
For starters, I totally agree with you that asterisked sound effects are less of an interruption than singularly complex sentence structure. Forcing the reader to go back and re-read a sentence just to try to understand what the blazes is going on when all they want is to move on to the next element in the plot is anathema to the goal of most VNs, which is, generally, to offer the straightforward entertainment of a quick jaunt through a story world, rather than the joy of ruminating on a particularly fibrous utterance.
However, *clears his throat*, I would like to point you at the hill you're about to go sliding down. It is, if I do say so myself, a slippery slope *wink*. My own personal experience with trying to use this technique was that use instantly turned to abuse *sigh*. Before too long, the dialogue was filled with all sorts of things that had no business being there; they weren't sounds being made by a speaker at all, but rather related actions which, if they needed to be communicated, belonged more properly in a narration line, and if none was available, why then the dialogue itself would have to carry the meaning *shakes his head*. It simply doesn't make sense for characters to be communicating quite so much in what is, ultimately, a poor excuse for narration *nod*.
In a nutshell, I found that the technique simply did my script more harm than it did my script good. The same is true of the use of italics in scripts I've read: I have seen them used only once that I can recall, in an official translation, and while once or twice they were helpful, much more often they were completely unneeded and simply served to call attention to themselves and look out of place. When a tool causes you more harm than it does you good, it's better to simply force yourself to throw it out and work under tighter constraints. Art has always and will always flourish under constraints, and I personally have not found it particularly onerous to go without this one tool; on the contrary, I've relished the change.
Aside from their usage to introduce lists of things, you can also use a colon in place of a semi-colon when the half of a sentence after the colon is more like an illumination/rephrasing of some part of the first half, rather than a separate, related, independent clause. It's kind of an advanced technique, I guess? I don't mention it in the guide both because I don't have a solid handle on the rule myself and because I think it's not really a necessary thing to do (there are plenty of other options available), but I certainly do use colons this way myself from time to time without much thought. Your usage looks perfectly cromulent to me.
(I would probably always assume the former interpretation, not the latter, without some strong contextual evidence otherwise, and I would probably only find it not to be a somewhat odd utterance when coming on the heels of a request for help putting on a seatbelt.)