I've installed Protector 3.35 and Altsys 7.1 in a fresh installation of xoops2.3.3. The install of D3Forum seems to work, except for the admin_menu_php constants and the preferences constants - they are all undefined after installation.
1) The TITLES in the Forum >> Quick Links display (except preferences) are blank and most of the TITLES on the preference screen are blank too.
2) I get this error (and similar for each constant):

Warning: constant() [function.constant]: Couldn't find constant _MI_D3FORUM_ADMENU_CATEGORYACCES in file XOOPS_TRUST_PATH.'/modules/d3forums/admin_menu.php' line 7

3) All other constants seem to be initialized correctly (english).
4) The module itself is working fine, near as I can tell.

5) As an aside, the title are missing from the xoops admin menu and preferences, but preferences selected from the index (across the top, once editing has begun) display just fine.

I tried installing /extras/altsys_functions.php but that broke xoops completely. I assume there's something I've overlooked in the altsys module, or possible in the xoops preferences themselves, but I don't see it.