This is not a helpful way to enter Imperial dimensions, and the examples suggest that the writer doesn’t normally use them (eg, “1 in + (1 / 3) ft” and “1 ft + (1 / 3) in” are both highly unlikely in practice).
I routinely use metric to design plastic parts, but imperial to design with dimensional lumber. Expressions could be helpful when I need 2’ 3 57/64" + 1 3/4", but I need to be able to enter it just like that.
Imperial is convenient when used as intended, but it does not fit a Metric usage model.