It has nothing to do with loading from the optional directory.
This extension fails the ACID test, i.e, boot TC with base norestore nolocal then load the extension via appbrowser. If it does not run then it is an issue with the extension. To see what the issue is, open an xterm and type soffice. You will see that it cannot find needed binaries, .e.g., soffice.bin being one.