1. I don't have the error you reported (I am using CodeStyling Localization 1.99.29). Have you some special debug settings?
2. I am aware of the compatibility warning displayed by CodeStyling Localization. I anm using load_plugin_textdomain to load the polylang textdomain.
In Polylang, you have the possibility to choose the language from content (see Polylang settings). That means that the language code is not included in the url for posts and pages. This has some pros and cons. Among this, Polylang needs to delay the textdomain load (normally done before the content is known). So Polylang uses load_textdomain to do this. This function is convenient as I don't need to know what sort of text domain it is (default, plugin, theme). To avoid this compatibility warning would need more complex code and, up to now, no issue (except this warning) was reported. I am using both plugins and never got any conflict.