Dominate and Haste could still be Twinned under that criteria since the issue is not with multiple rolls but a singular roll affecting multiple creatures. Fire bolt has always been unable to be twinned by a strict reading of the spell, and Hex, Hunter's Mark and Heat Metal were always not eligible (doubly so for Heat Metal since it doesn't target a creature)
Also being Hasted to be able to Dodge, Disengage or do other stuff so you can spend your normal action to cast a spell is extremely helpful.
Well, "singular roll affecting multiple creatures" is technically one of the things the errata doesn't like, but that's besides the point I was trying to make... Dominating an enemy can make you force that dominated creature to perform some sort of action on another creature that would require a saving throw (say, grappling), thus causing that spell to force multiple creatures to make saving throws. Same goes for Haste, the haste action can be used to force saving throws on multiple things, or even used in an attack by someone with the Sweeping Attack battle maneuver to "make a roll of any kind that affects more than one creature".
Now, this is up to interpretation of the intention of what qualifies as within the scope of the spell or not... A dominated creature isn't using any supernatural skills or abilities, it's just using what it could always use on targets of your discretion. Dragon's Breath, the spell this errata was aimed at resolving, grants affected creatures a special action that's described as part of the spell itself, and is therefore "spell-ier" than something a dominated creature would do... But then again, so does Haste.
One could argue that Haste is still allowed because everything included within the limits of the hasted action are things the creature would be able to do normally, whereas characters normally cannot use a breath weapon as in the case of Dragon's Breath. ...but, then, is it allowable to use it on Dragonborn, who
can use breath weapons normally?
That's an awfully strict interpretation of Fire Bolt though, and one I doubt is shared by much of the community considering the general consensus seems to be that twinned Fire Bolt is legit... Or at least was. It's now definitely in the bin though; along with Levitate, Enlarge/Reduce, Otiluke's etc.
That interpretation is however supported (in as much as it isn't unambiguously rejected) by an earlier SA of Crawford's, the "Twin Spell test":
Twinned Spell test: can the spell affect only one creature at the spell's current level, and is its range not self? If yes, TS works.
...which, by similar interpretation, excludes things like Gaseous Form and Invisibility, since those also affect the equipment worn by the targeted creature. So I guess those are out, too.
Anyways, fun times with stupidity: Say you're an Illusionist at 14th level or higher, and you've got at least one concentration-free Major Image following you around... You then shape the image into, say, a rock or statue filling up the full 20' cube, and use your 14th level ability to make it "real" for 1 minute.
You then cast True Polymorph on the object, turning it into any creature smaller than the object (considering it's a 20' cube, that means pretty much anything).
So... First off, that probably shouldn't happen at all, even if it
is a "real" object... It's still a "real" illusion. But if it did happen, would the creature be able to attack or cause damage? Is the polymorphed creature still the "object" created by the Illusory Reality, and therefore bound to Illusory Reality's limitations... Or is it now under the magical rules and laws of True Polymorph?
Only if I can play Hagrid with Agragogigaogogog
Q: Are the spiders in the Forbidden Forest uninterested in Harry Potter?
A: No. They are agog.