I have had my own troubles with recommended torques, most recently tightening the clamp on an ultra-light CF handlebar. The bar cracked at half the recommended torque. My LBS tells me that recommended torques are BS, sometimes meant as maxima, sometimes meant as the actual recommended torque, sometimes just plain wrong. They said they never use a torque wrench but just substitute common sense instead. Well that can be a problem for us amateur folks, who don't possess a lot of that commodity.

But just following the common sense approach for a moment: 9.8 Nm sounds crazy tight for chain ring bolts, does it not? I would much prefer about 3 or 4 Nm with a little Locktite. Those rings aren't going anywhere!

I empathize with OP. Been there, done that. You don't get to be a good bike wrench without breaking a few bolts. Aggravating, yes, maybe even avoidable, but not catastrophic.

Robert