Fuselage changes most likely come from Engine decision more than anything else. My guess is when the first model was presented the idea was to equip it with the 2xT700-701D (2x2000hp) engine which is being license built by TEI for the T-70 project.
Maybe TEI and SSB had hoped they could make a deal to produce the engine for the ATAK-2 project at the time and build them directly in Turkey minimzing production time of each Helicopter while the development of an indigenous 3000hp class engine similar to the T901 is under way to be used on future T929 Blocks and the T925 project.
Most likely through either fear of future export restrictions (Pakistan case with T129) or sanctions(CAATSA) plans changed and TAI and SSB pivoted their gaze to Ukraine for the engines.
And to fit the ukrainian engines changes to the fuselage were necessary. As eastern engines tend to be bigger to their western counterparts.
My question here would rather be in the future when our own 3000hp engine is ready will we see future block have an redesigned fuselage (smaller engine) or would it be smarter to continue using the ukrainian engine for ALL T929 production even after the indigenous engine is ready to save money and time and focus on a new coaxial rotor attack, similar to the Raider X, to slowly replace the T129 in service from 2040+ onwards. Seeing how the T129 is pretty growth limit and the Phase 2 updates already got everything they can from its fuselage.
Ukraine shouldn't make any fuss about exports regarding the engine and honestly if the performance is satisfactory I would see TAI rather focus on new technologies for future Attack and Transport helicopters for the Military and export market.
Of course this all hinges on the plan for the T929 still being the same as 2 year ago, first ones equipped with foreign engines and then at a later date the switch to indigenous engines once it is ready. Now with the ukrainian engines it could change.
For the wing design. I have no idea what TAI is trying to accomplish with it. Both the wing design on the T629 and T929 seem pretty weird to me and having conventional flat wings seems would be better?