{{msg-nocc|Html_contacts|notext=1}}
What the parameter %1$s does stand for here? A number? Then plural template should be used.
The same is valid for message Html contact count.
NOCC has no plural support for L10n, unfortunately. Please report it in its bug tracker.
If it were a number, I think it would have been %1$d. I looked it up in the code. "%1$s" is replaced by a config string. "NOCC" is the default value.