Are these any worse than in other editions?
Even 4e, which was at the tighter end, had some uncertainties in its rules (eg what happens when a character becomes dazed partway through their turn? My group first ran it that a character got to keep their full action economy from the start of their turn, but then - after a bit more play experience - by consensus changed our approach, so that a character who became dazed after having already taken at least one action was forced to end their turn).
AD&D was rife with uncertainties. Was 3E immune?
I'm not going to try and analyse all of these. The stealth issue is well-known, and the Stunned one seems like an obvious error. But here are thoughts on a few of the others:
*
Heavy obscurement: "A Heavily Obscured area—such as an area with Darkness, heavy fog, or dense foliage—is opaque. You have the Blinded condition (see the Rules Glossary) when trying to see something there."
The blinded condition causes disadvantage on attacks; so if a character is blinded when trying to see something in a heavily obscured area, it would seem to follow that they would suffer disadvantage (the conditional language "when trying to see something there" seems intended to signal the conditionality of the disadvantage on attacks).
*The whole hand-shield-spell thing is a ridiculous consequence of sticking to the legacy of VSM components.
*Divine Intervention: the rules text seems clear enough - it's a bonus 5th level spell slot once per long rest, that doesn't require material components and has a 1 Action casting time. It seems pretty clear that it's meant to encompass Raise Dead (among other spells; in fact the Basic Rules on DnD Beyond don't seem to have any 1 Reaction cleric spells). Is the concern with Hallow that it breaks the game to bring Hallow into play in that fashion? Or just that it's silly, and tends to render the 24 hour casting time pointless?