I think Things aren't going as expected with UK. The contribution of BAE in TFX Phase-1 was very mediocre with mostly inexperienced engineers and Tusaş complained about this situation a few times. As for engine to be likely developed with RR, RR put strong cards on table both in terms of license rights and production since they feel that Turkiye don't have an alternative way out of their offer. Also, Some reluctant statements by Turkish officials regarding possible deal with BAE for TFX Phase-2 were reflected in the press. Turkiye's cooperation offers for Tempest were also rejected by UK. The withdrawal of British royal air force which was said to join the last AnatolianEagle exercise also created question marks. Apart from this, there is a serious political confrontation and embargo from the West in almost every field, be them enlargement of NATO, terror operations or Russia/Ukraine war. Considering these conditions, TEI/TrMotor must have been given an unofficial development task for Tf35K engine as a precautionary measure. If everything was fine with the RR, no one would work with 300 engineers on the design of the engine on an engineer/day basis. RR's capability is indisputable but we all know what we are going to face when it comes to matters related with Turkiye bro.
I know wiki isn't reliable source, but I was thinking that continuing with Ukrainian design company is for the sake of the unmanned vehicles potentially crossover to jets if necessary.AI-25TLT(Black Sea Shield - turbofan) The AI-25TLT licence-built by Turkish-Ukrainian joint venture BSS based in Istanbul for the Bayraktar MIUS[4]
AI-25 has been used for several trainer jets and is a very well tested engine, so having it license produced in Turkey (like China) would be very good for us. even if it says license built. I'm not sure it's being license built in Turkey or just assembled, as I don't think we know how much of the engine parts are produced domestically.
I don't think we'll get anything worthwhile cooperating with RR, as they're there to keep the R&D process at a certain pace, which could ultimately mean slowing us down. Remember that US-Brit doctrin is ensuring technological superiority of their allies, e.g. Israel and if they can't destroy R&D they can slow it down and hope to sabotage it through delays and political strife.
Thus I think AI-25 and our cooperation Ukraine is important in that regard and being able to make it with domestic means would ensure cost effective solution in the intermediate term while we work on our own engine.