hi eaguilar,
The way I see it, based on your setup:
- You should not have LACP configured on neither EX chassis nor SRX cluster
- When EX member 1 is DOWN,reth1 is DOWN and you wont be able to ping 10.10.0.2 but 10.10.0.1 because reth0 remain UP
- Your reth0 should contain (ge-0/0/14 & ge-5/0/15) because when EX member 1 is DOWN and you want reth0 to remain UP
- the SRX cluster is UP which I assume you are using direct links between SRXs?
If you beleive you have exhaust all config setups,I would troubleshoot L2 on the switch by baselining before and after EX member 1 is DOWN.