Alan Warnes said (back in July 2017) that TAI was aiming to announce the deal by/at the Farnborough Air Show.You are right, election manifesto is no confirmation of the ATAK contract being signed.
There was a ceremony when the Milgem MoU was signed in May 2017. Here we are talking about the final contract ... No announcement / press release, no official statement.
Few weeks back, some Turkish media outlets reported that the Milgem loan of USD 400 million was finally approved after some problems and funding for T129 was under process and not secured yet.
So, too early to celebrate.