Regular expressions are not supported for extended communities. In addition, an extended community match statement matches with a route's extended community if at least one of the extended communities in the match statement matches with the route's extended community. There is no need to for all the extended communities in a single match statement to match with the route's extended community.
For example, suppose the policy file is the following:
entry one {
if {
extended-community "rt:64500:20000 rt:10.203.134.5:40 soo:64505:50000
soo:192.168.34.1:600";
} then {
permit;
}
}