OK, the game is barely out the gate so its a bit early to suggest variants but I will anyway.
Two parts; can be used together or separately; would perhaps make more sense together...
1 Total "Riot points" - now a roll of d4 (d4+1 in 1900s and d4+2 in 1910s) changes to number of Unrest tokens the target has PLUS the (same) die roll.
Yes, potential to make a riot devastating but that's what riots do.
In my one game, I got 8 Unrest (half due to others) and a Riot went off. So in my suggestion above, I would potentially see 14 Riot points in the 1910s (d4+2 plus the 8 Unrest).
2 Rather than nicely finding your opponents properties to destroy, once the initial lot is picked by the Instigator, subsequent Lots targeted are from a d4 roll: 1 is North, 2 East etc. If a second Lot destruction is followed by a roll sending back, then spend an RP and continue on. Also spend a RP if you are moving against a boundary.
Thematically, it makes sense that a Riot proceed on its own and not be "guided" for max damage. So if the Instigator knows the Target will have a lot of RPs, they need to exercise discretion when picking the initial Lot for the Riot.
So while the threat of a Riot's destruction is larger, taking Unrest and wisely choosing a Riot's initial lot will require a moment to think about it...
Feel free to variate away! The ideas are interesting and just so you know the original riots were way more exciting BUT they added a ton of time to the game. They were adapted to be more surgical and quick for general gameplay, but we never had anything quite like what your describing. If you play with this variations please post a session report or a message as to the results, I'd be eager to hear about it.