Your frame as a steel frame made from a high quality chromium molybdenum steel is generally quite tolerant of torque. Thus, it's not as important to have precisely the recommended torque as it is for e.g. aluminum alloy frames.
As far as I know, the only parts screwed to the frame that are essential to riding the bicycle are:
- Bottom bracket: you will find the recommended torque given by the bottom bracket manufacturer, but 40 Nm is a good guess.
- Thru-axles for wheels if not equipped with QR: many thru axles have the torque written on them, if not 10 Nm is a good guess. However, your frame does not use thru-axles.
- Brakes (disc or rim): you will find the recommended torque given by the brake manufacturer. For caliper brakes (like what the Steamroller uses) about 8-9 Nm is a good starting point.
Then there are obviously components screwed to frame threads that are unnecessary for general riding, such as water bottle cages, fenders, pannier rack, etc. For a good guess for these, you can use any generic bolt calculator. Of these non-essentials, the only that you have to get absolutely right is the pannier rack if you're carrying a lot of cargo, as it is a load bearing component. 5 newton meters for the pannier rack is a good guess. You are unlikely to damage a quality steel frame with 5 newton meters. The others (fenders, bottle cages) can be left slightly undertightened as they are unlikely to vibrate loose unless left very loose.
For any other component, it isn't attached to the frame threads so you won't find the torque spec given by the frame manufacturer but rather the component manufacturer.