Ah. Guilty as charged. Sorry if I was a bit blunt in my crit. I had to have my tact gland removed many years ago, after an incident involving a fork, a badger and a trampoline (best not to ask)
Anyway, I'm sorry if I didn't expound on ways to crank it up. You don't see many queries for thrillers, so it's hard to know what works. But I think the main thing to include is a sense of danger. That's one of the defining characteristics of a thriller, along with the ticking clock. Thrillers typically have scads of tension created by high stakes and tight timelines. If so-and-so can't prevent such-and-such by teatime, the west coast is toast! sort of thing.
What you need to do, I think, is work out what the stakes are. What are the consequences of failure for your MC, and then ripple it outwards - consequences to nearest and dearest, consequences to society, consequences to history. That last one may be tricky, but it's what makes your setting so integral to the story, why this is a
historical thriller. How is [whatever goal] important in the grand scheme of things - how might it change history if it happened differently?
But whatever the stakes, thrillers mean suspense, tension, excitement, danger. The query needs to make us feel those.
Good luck