Translating CR LF to HTTP/1 headers

In http://http2.github.io/http2-spec/#rfc.section.10.3

"""
An intermediary that performs translation into HTTP/1.1 cannot
alter the semantics of requests or responses. In particular,
header field names or values that contain characters not
permitted by HTTP/1.1, including carriage return (U+10) or line
feed (U+13) MUST NOT be translated verbatim.
"""

So if U+10 and/or U+13 are included in HTTP/2 headers, what
should intermediary do to translate them into HTTP/1?  Just
remove them or replace them with safe characters? The meaning of
the headers may change with these changes, especially if those
characters are permitted in HTTP/2 headers.  Returning 5xx
response may be an option. But there is very interesting
situation. If all machines in the path are HTTP/2, then the
request succeeds, but if one of them is HTTP/1 then request
fails.

Best regards,

Tatsuhiro Tsujikawa