Using PPSSPP 1.4.2 not only the menus are translated for me. I just started the game and the text after the intro video is translated. Also, every piece of text in the kingdom select screen is translated (of course, the voice is still Japanese).
Therefore your issue seems to be due to your patch or patch process. Maybe there are different releases of the game as well. I downloaded the patched iso directly, so I cannot help in that regard.
Therefore your issue seems to be due to your patch or patch process. Maybe there are different releases of the game as well. I downloaded the patched iso directly, so I cannot help in that regard.