"Tretubi" is Italian for "three tubes" and is a generic term for a frame where the three tubes in the main triangle use a higher grade alloy than the stays and fork blades, typically to lower costs, at the expense of lightness. In the case of the posted specs, the main triangle is higher strength chromium-molybdenum, while the forks and stays are cheaper and lower strength hi-tensile steel.

BTW, my sanity is just fine. I made my assessment based on the reported post diameter which is consistent with a lightweight hi-tensile steel but atypical for butted CrMo. Any other knowledgeable forum member would tell you the same thing.