Vim errorformat multiline string

I'm trying to parse this error output for Flow. In the first error, it's the second file and line number that really matters, not the first. I would like to tell vim to use the second file entry. (So in this case, the location list should jump to source.js line 94, not line 20)

/Users/asdf/source.js:20:22,34:1: property hidden
Property not found in
/Users/asdf/source.js:94:10,106:3: object literal

/Users/asdf/source.js:25:14,18: identifier strin
Could not resolve name

Here's the error format currently defined for flow: It works except that it uses the first filename instead of the second.

let errorformat =
    \ '%f:%l:%c:%n: %m,' .
    \ '%f:%l:%c: %m'

Attempted Solution

I've been trying to use multi-line error formats, but I don't know what I'm doing. After reading :help errorformat, it seems like something like this should work, but it just loads the whole error into the message, with no file / line information. It also matches the second error using the first entry rather than the third.

let errorformat =
    \ '%E%m,%C%m,%Z%f:%l:%c:%n: %m,' .
    \ '%f:%l:%c:%n: %m,' .
    \ '%f:%l:%c: %m'

Update

Thanks to lcd047, who pointed out that I'm not matching the correct output. Syntastic formats the error as follows, all on one line:

/Users/seanhess/projects/serials/web/app/model/source.js:20:22: property hidden Property not found in object literal (/Users/seanhess/projects/serials/web/app/model/source.js:94:10,106:3)

So, new question, how can I match the second location instead of the first? I think I'd prefer to ignore the first location.

Update Answer - this worked:

let errorformat =
    \ '%.%#: %m (%f:%l:%c\,%.%#),' .
    \ '%f:%l:%c:%n: %m,' .
    \ '%f:%l:%c: %m'

You are not getting the file/line information because the %E specifies to use the rest of the line as the beginning of a multi-line message.

Try changing the "%Em" to "%E%f:%l:%c:%n: %m" for starters, since you basically want to keep all the original data being grabbed from the first version of errorformat.

You may want to change the "%Cm" to "%+Cm" to capture all of the lines in your error output.

The "%Z%f:%l:%c:%n: %m" looks good and should be used on the second line, since the %E will catch the first one.

Try that.