Colnago's EPS and C59 are both lugged carbon fibre bike frames dating from the 90s, when CF was a new material. They had a reputation for unreliability (I don't know if that was the construction, or something else.)
Whether you'll find one new, or used and in good condition is a completely different problem. The lugs and the tubes are fastened together with epoxy, which makes swapping out a tube difficult.
Also, the stress point on the CF tube is now where it enters the lug. The modern monocoque construction of a CF frame does away with those stress focus points, so "should" last longer. Plus popping the frames out of a mold in one piece is a lot less work than assembling and epoxying tubes and lugs.
Answer: No you can't just change tubes, because the tubes are epoxied into the lugs, and you couldn't change just one because the angles of the lugs would require all joints loosened to slide apart.
Homework: OP should consult with a local carbon frame maker/repairer who can give a definitive answer.