I haven't used any of these modules either, but based on the evidence you've shown, it seems like the "legacy" behavior of "Locale::Maketext::Extract / xgettext.pl" is sub-optimal (to put it nicely) because it is non-compliant with the other tools that it is supposed to interact with.

No, that is way too strong. They are compatible: they both use "#:" to indicate the source (filename, line number), although one uses one line per entry and the other combines them in one line; and they both use "#." for variables. Their relative order is not actually important. (See the included doc Web localization in Perl in the distro)

It's just that diff sees them as different.

In fact, I wouldn't be too surprised if yet another tool would use yet another (compatible) format for the same data! So, making this module and this one tool compatible is likely not going to fix the problem. Not definitely, anyway.

It's just a formatting choice. The difference between these formats is actually much smaller than the different output options for diff itself (for example: unified diff vs. normal diff), which you can control with command line switches.

So I propose to either use an output format option, possibly in this module (you can use explicit control for every option, or a global named setting, or both), or add an external command line tool to convert any of these compatible outputs to a single common "standard" format. In fact, I think the latter is the most universal practical solution. You may add the formatting options to this module, and build this command line tool on that!

I would not just change the format to match the "tool du jour". It won't solve anything in the long run. And no tool will barf on the data just because of this tiny format change — except diff. :)