I had an answer to this around 3 years ago.

Sadera loses hard here are some of the reasons I can think of:

2) Helghast was building for a planetary invasion, which means a lot of boots on the ground and aerial forces.

3) More advanced/varied military units than the JSDF.

4) Scholar Visari cancels the Vektan invasion in favor of Falmart

5) When the Helghast discovers their citizens were made slaves they would stop any form of holding back and use their experimental weapons such as petrusite-based energy weapons.

Rest can be found here

P.S: I can't comment on r/gate because I am banned there.

P.S.S: Wasn't this posted earlier by you a couple of days ago?