Does this occur with other types of fittings as well? If only bends with circular sections are the issue, you can calculate the surface area algebraically using available parameters (radius, bend radius, angle). For other fittings, remember to remove the surface area of the open faces as the the Solid derived from the object will include all faces, which will not accurately reflect the outer surface area.
To calculate the area from the parameters ‘were not an option’ due to lack of any kind of consistency in the vast amount of families used. Though it seems to be the only option to find the right parameters one by one. @Kulkul solutions seem to be a great option to recreate the geometry. Monday maybe on Tuesday I’ll have a further look.