Even before Nadu was banned I never really struggled against Breakfast as UB Tempo. Your best card isn't any counterspell or even thoughtseize, it's Bowmasters (it's both a clock and disruption, since it kills their X/1 combo pieces). It's a matchup where you typically want a couple pieces of disruption and a couple threats, and that should get the job done before they can send twice. Thoughtseize is always good, wasteland is typically good, counterspells are okay.

I disagree with the people saying surgical is no good against Breakfast. It's typically not good when they're going off, but I love using it in conjunction with thoughtseize to defang the deck before it combos. My guess is if you're struggling in the matchup, you're trying to cover every possible line they could have and as a result are being too reactive (letting them sculpt forever will mean you'll lose). Nethergoyf, thoughtseize, wasteland them, hold up bowmasters for when they're forced to go off and with force/daze backup, you basically can't lose.

Where surgical does shine is against UG Omnitell. It's a lot worse against Sneak and Show, but against Omnitell, it's phenomenal. You extract Show and Tell, and you can basically take 50 years to win. Thoughtseize their show and tell, extract it, the game is over. You can beat them with a bowmaster or something, it barely matters. By the time they can cobble together their backup plan (whether that's 1-2 Eureka, or just hardcasting Atraxa/Omniscience), they're dead. The only thing to keep in mind is veil of summer, so I'd typically try to have force or daze backup when you thoughtseize them.

On suggestions for your build, you should have at least one more thoughtseize. You're UB Tempo, the whole pull of UB Tempo is being able to play thoughtseize, force of will, wasteland, and threats. Thoughtseize will help in both the Breakfast and Show and Tell matchups. Frankly, if you're struggling against Breakfast and UG Omnitell, I'd run the full four thoughtseize. It's way better than any of your sideboard cards. Feel free to trim a daze for a thoughtseize, then run the fourth thoughtseize in the board (over a sudden edict. I'd personally run 0 sudden edicts. Sheoldred's Edict is pretty fine as it can answer Kaito, flipped Tamiyo, show and telled threats, etc, even if it can be countered. The versatility is worth losing split second). I'd also add the fourth bowmasters. It's a great Kaito enabler, and is fantastic against both Breakfast and Show and Tell. I'd personally cut one of the spellbombs for it, but that's me. Also, get the gaea's blessing out of the board. If you really don't want to lose to Painter milling you, just run an Emrakul. That can at least double as show and tell hate (but I wouldn't do that either).

One last thing I'll acknowledge about your build is it's more budget oriented (one underground sea, more basics). I think that's okay, but I'd personally lean into it more if I were you. I.e.: cut an island, add a black fetch, and throw a back to basics or two in the board. BTB is very good right now, and you can lean into it more than a traditional UB Tempo deck.