bitcoin/bitcoin#22151 could give additional input.

Concept ACK.

I'm a little bit unhappy about how much extra pre- and post-processing needed to use XLIFF. Apart from the translator comments it was working fine with .ts. This makes the pipeline even more complex and difficult to troubleshoot. Then again there is no way back now, at least for 0.22.

Is this still compatible with releases that have .ts translations? It might still be necessary to do imports for 0.21.x releases. Or should we use an old copy of the script for that. Also fine with me.

I'm a little bit unhappy about how much extra pre- and post-processing needed to use XLIFF.

Yeah, the additional steps, besides just lconvert calls, are unexpected. OTOH, there is a possibility to drop (now) intermediate TS files. Of course, such a change should wait until TS files support goes out from our time horizon.

Is this still compatible with releases that have .ts translations?

Yes. That is one of this PR goals to keep 100% compatibility with TS translation files.

Rebased due to the merging of #102.

Tested ACK 2fcdb51

The only difference I see in the .ts files afterwards is that every single message now has status unfinished. While this generates a huge diff, it doesn't seem that the status affects Qt's use of the message. E.g.:

     <message>
         <source>Right-click to edit address or label</source>
-        <translation>Rechtermuisklik om het adres of label te wijzigen</translation>
+        <translation type="unfinished">Rechtermuisklik om adres of label te wijzigen</translation>
     </message>