Is OS X Installer package postflight localization supported?

I've created an OS X installer package that includes localized resources (License.html, Readme.html, etc.) In particular, it includes a localized postflight script, since some of the post-install actions differ from language to language; opening a per-language file after the install completes, for example. The package is created as part of an automated build, not through Package Maker.

Originally I used the 'full' locale name as the localized Resource folder name; for example, English.lproj. Everything worked fine. Recently, I switched to the ISO name, i.e. en.lproj, since I discovered that was what Package Maker was using, and this question indicates that form is preferred. Everything worked exactly the same, except that the postflight script is no longer executed.

I did some more testing, and noticed that, even when it works (using the full language name as the name of the folder), it logs this message to the console:

Local开发者_StackOverflow社区ized installer script postflight found in the <name> package. Using compatibility mode.

I can find barely any mention of Installer localization in Apple's developer docs, much less anything specific about scripts. Does anyone have experience with this? Is it a bug for it not to work with en.lproj, or was it a bug for it to have worked before?

Things that I don't understand:

1. If you're not creating these packages with PackageMaker, what are you creating them with?

2. Why would a postflight script ever need to be localized when conditional logic would almost surely suffice?

It turns out that, no, this is not supported anymore.