So far I have tried three German speechpacks on SH4 using JSGME, but none works flawlessly: the official SH4 German speechpack, the GWX 2.0 speechpack and the Spax pack. In all cases, speech concerning torpedo launching/reloading reverts to English: you get "Torpedo in the water", "Torpedo impact", "No. 1 tube ready" etc instead of "Aal ist im Wasser", "Torpedotreffer" and "Rohr 1 nachgeladen, Herr Kaleu" etc. Next step was to remove the contents of the 1.5 speech folder and use this to create a new JSGME-ready US Speechpack, the original speech folder remaining empty. Tested this with the US speech disabled and GWX speechpack enabled, and the US speech regarding the torpedos had disappeared.......... to be replaced by dead silence.
Next step will be to see if the official German SH4 speechpack works properly with the US speechpack disabled, including the speech pertaining to the torpedo firing.