I understand your point for the time (I didn't think that far indeed) but it shouldn't be an issue actually because even if you miss the event you can simply trigger it the next Saturday since there is no event which actually proceed to the wedding without you. So at the moment, Utako can't be locked out of the good ending as I thought at first. Not sure if this is normal or I missed something from CarpeNoctem's code. I'm checking with him.
And the warning event fired for you because there is indeed no condition to only trigger it in the morning which I'll fix in next patch thanks to your feedback.
For Lily, you have a point. But we could stretch it she's worried about being found out by Anael if she fools around too much in public
For Hikari, I would need a save file to check on my side. contact(at)gaweb-studio.com if you can share your file
Thanks!