Parallel forces questions

Why is torque error likely to be large?

Can an error in one measurement be negated by error in another? Why?

You need to be much fuller in your question. You specify parallel forces. Parallel forces at a distance to each other create a torque. This much is absolute. There is no error here.

But the error (if any) depends on the specifics of both the experiment and of the measuring equipment. Unless that is detailed there is no way to address your issue.

The other part is that YES it can occur.
There are two classes of errors. RANDOM errors which means that if you repeat the same measurement you will not get the same result,
These errors never cancel. They have to be mathematically considered.

And SYSTEMATIC errors.
In the design of the experiment it is quite possible that one systematic error can cancel another.
More than possible. It is the mark of a well designed experiment that this should always be attempted.

A scale that is not correctly set at zero will always read high, So you get a tare weight and simply allow for it. that is an example of the error in zero being used to cancel the error in another reading.

I pondered your question earlier, and as you have re- submitted it, obviously you got no response. That's because I think no- one understands what you are asking, as I don't.
Maybe you might explain?