What complicates the matter is that strut is a stressed member. Fabricating a bit of steel is the easy bit, getting it in there is somewhat harder
Imagine trying to replace a spreader, and you have to get the rig tension and mast bend back to where is should (must) be, without touching the turnbuckles or addind any significant weight aloft.
Its certinaly not beyond the wit of man to complete, but considering the implications if it goes wrong the amount of planning, peer review and analysis that goes into this will be significant