ALL the program does is speed up the calculations, and i will explain those.
like everything, it's complicated and mystical until you understand the how and why - which you can then promptly forget.
The industry hasn't changed in the last 50 years probably, so every design that can be done, has been. I am amazed I even have a job - or had one.
For example there is probably a formula somewhere for calculating the power you can get on a core size, but no one uses it, because we all know that a
29 by one is 50VA. I have access to over 10,000 designs. Somewhere the one you want has been done before.
What I would say to anyone thinking of making their own transformer is, DON'T. There are hundreds of transformer companies in the country, and I suspect that applies to a lot of other countries. they have access to the materials and equipment, and can design it for you. Unlike virtually every other component out there, you can order a small batch, or a one off.
If you wanted a 50va that was really special, with 12.43V secondary and a 123v secondary and a primary of 98V, it would be the same as ordering a Big Mac, no relish. They don't have to order in different buns and processed meat substitute, they just make you a standard burger, and don't put in relish.
It's not like asking Intel for a Pentium chip with a slightly different clock frequency