[Exim] Exim 4.10 system filter: adding multiple headers

Hello,

I'm able to add a custom header, from a system filter, to an incoming message.

following the doc, I can also add two headers by using a "\n" separator.
This works, and both headers are visible in the delivered message.

my problem is that if I add more than one header with this command, I can't
reuse those headers in exim's router config:

here's my condition in exim.conf:

${if >={$h_X-SpamLevel:}{100}{yes}{no}}


it works after this command:
headers add "X-SpamLevel: 12"

but not after those:
headers add "X-SpamLevel: 12\nX-SpamDetail: subject line"
headers add "X-SpamDetail: subject line\nX-SpamLevel: 12"


thanks a lot for any hint/help,

Bill