Hi Alex,
Yes I have tried both lacp and non-lacp before but they are still the same.
Here are the interfaces between SRX and EX:
SRX-A ge-0/0/14 ---> EX1 ge-0/0/46
SRX-A ge-0/0/15 ---> EX2 ge-1/0/46
SRX-B ge-5/0/14 ---> EX1 ge-0/0/47
SRX-B ge-5/0/15 ---> EX2 ge-1/0/47
Since the EX are in a virtual chassis, I assume that's how they should be connected in regards with the link you have provided.