vermiculus

The field is likely not being monitored for replacement, and it’s likely in an entirely different table of the database.

Having a similar snafu with post titles over here, by the way—just the standard text replacement, though.

Just a humble user here, but I truly doubt that this plug-in searches all text on the page when it does the replacement. WordPress works by using databases—a giant collection of tables filled with information. There are columns for users/passwords, post titles/content, etc. This plugin (probably) works by interjecting itself when WordPress looks at specific columns of specific tables in the database; it probably doesn’t even look at where the sentence “log in to reply” is being held. There is a way to change it directly, but this plugin is not your answer.