Can you try configuring remote-site id for each of site's interface and check something like below:
HUB:
set routing instance hub protocol l2vpn
{
site 1
ifl I remote-site-id 2
ifl 2 remote-site-id 2
ifl 3 remote-site-id 3
ifl 4 remote-site-id 3
}
Spoke 1:
set routing instance spoke1 protocol l2vpn
{
site 2
ifl I remote-site-id 1
ifl 2 remote-site-id 1
}
Spoke 2
set routing instance spoke2 protocol l2vpn
{
site 3
ifl I remote-site-id 1
ifl 2 remote-site-id 1
}