Any other transformer with 20VAC 3 ~ 5VA output will do the JOB, even an external one!

230Vac Main
75Khz
Voltage with no load : 110V

4A load : 106V
8A load : 102V
12A load : 97V

Load are 424W - 816W - 1164W

Primary winding are 10 x 0.1mm wire

Secondary 15 x 0.1

Hope that helps

Inductors, they should improve performance, but ludo got a nice results!, but they can be added
I think he needs 15uh on -26 core material