To answer this question we need to look at the whole situation. Ali was only able to use 2x15mm fans because he used a 240mm rad that isn't supported by the case (30mm thickness). Hence when using them he still had bulging in his top panel. Maybe if we would have used 12mm fans it would have fit better.
So answer 1: if you use any rad other than the LT240 you are going to be required to do the math yourself to figure out what works.
Answer 2: if you use the only supported 240mm rad you will be able to use 1x15 and 1x25.
I hope this clears that up. At the end of the day pushing the boundaries of this case is going to be fun but realistically no one can answer your questions at the moment unless the items fall within the specs.
My point is that it's only 1x15 and 1x25 if you have the LT240 rad between the panel and the fans, due to the differing volume of space between the mobo and the rad, and the psu and the rad.
I believe the available space changes depending on if you do panel, fan, rad or panel, rad, fan.
If the fans sit between the panel and the rad, I'm assuming there's only room for a constant space between the panel and the rad, otherwise, I can't picture how you could fit 1x15 and 1x25 in the space between the panel and the rad. In this configuration, there should be almost no space between the rad and the mobo, since the order would be panel, fan, rad, mobo.