Er, yeah, because they were always stopped before things escalated into war. So what's your point?
There's no "before" as such, no logical criterion of whether the Romulans stopped short of some systematic limit. There's just the UFP deciding that whatever mass murder the Romulans committed this week must
again count as "before", because the UFP never goes to war over anything the Romulans do.
Romulans in some episodes are foiled before they kill anybody. Typically, though, they kill lots of people, and/or obtain key Starfleet secrets, and/or humiliate Starfleet in various ways. They always provide casus belli (if not otherwise, then by virtue of implicitly having violated the Neutral Zone treaty). Starfleet never bites.
The point is that
only the UFP would fail to go to war over these things.
The same thing could be said of the TOS Klingons. Or the Cardassians.
Not really. The only time the Klingons have an "audacious plan" is when they poison the quadrotriticale at K-7, and that's neither obvious casus belli nor something they get away with scot free (they apparently lose Sherman's Planet because of it). When Klingons violate borders, Starfleet mobilizes warfleets and invades back. When Romulans violate borders, Starfleet tiptoes and hopes the Romulans don't get mad because their violator was forced to self-destruct.
With Cardassians, there's a single episode where Starfleet shows restraint, and "The Wounded" quotes the rationale that the force is spread thing, apparently due to the recent Borg nastiness. When the Cardassians try again, Picard blows up a starship; when they still don't learn, Jellico places mines on a fleet of starships. When they after a long pause resume their efforts, Starfleet starts a war that leaves the Union in smoking ruin.
The point was that Sela's specific plot didn't make a whole lot of sense, but that was probably because she was an incompetent 20 year old kid trying to score brownie points with the Praetor and failing miserably, not because anyone was insane.
Somebody would
have to be insane if an incompetent kid were to be let to try something like that.
OTOH, rational people could well be using the insanity stratagem just as happens in real life, such as at the Korean peninsula. If you aren't a top dog, you can always pretend to be a mad dog. Foaming at the mouth is great protection against your enemies!
Timo Saloniemi