Hey Wolfcannon you must have missed Technical Readout 3075 which expounds on such RetroTech. The Titan might not have been listed but many or all of these early or first Mechs were inspired by the BattleTechnology issues that you are posting. The Battleaxe caused a minor continuity issue for us as it became a Davion product and we gave it to Marik. We did some more fluff and worked it out.
Also the XTRO Primitives (the first one just came out) addressed these Mechs. I'm waiting for the Warships listed in Strategic Ops to be designed.