Could you post an example? One complete drawn triangle, with measured angles to three decimal places (use the Angular Dimension2 plugin) and one dimensioned length.

And also a ‘failed’ attempt to draw the triangle with length and angles.

If it is a triangle, one baseline and two angles should specify the third vertex exactly enough with at most two or three decimal places in the angles. Especially at the small dimensions you are workng with. If the lengths were hundreds of km, I could see your problem potentially arising, but not with a maximum length of 8ft (<3m)

Maybe you aren’t rotating the lines ‘in plane’?

What tool? I don’t quite understand what ‘convert sides to angles’ means.