The problem is to get an accurate result. I expect that plugins will create post types in an ‘init’ action and it is likely (although not mandatory) that they declare the post type as translatable at the same time. It’s for example what I currently do when reading the file wpml-config.xml. I examined how it is done in WPML 2.0.4.1, and for sure the list is not accurate before (‘init’, 15) as been fired.
That’s the reason why I wait for ‘wp_loaded’. At which time in the WP loading process do you need the list?
Also, have you considered using GitHub for your code so people like me can help out where they’re able?
Not until now as I don’t even know what I could do / not do with it. What kind of features would you like to add to Polylang?