The F6 and F10 keys are rather helpful in both LibreOffice and Apache OpenOffice, suggest a close read of these resources:

https://help.libreoffice.org/Common/Shortcuts_Accessibility

https://help.libreoffice.org/Common/General_Shortcut_Keys_in

Note: the dynamic nature of development in LibreOffice has led to a number of changes in the User Interface--notably some menu and dialog items that are listed in the wiki and on-line help files are not always correct and the documentation needs additional updating.  Just ask if you get stuck -- LibreOffice Nabble based mail list is here http://nabble.documentfoundation.org/Accessibility-f2006038.html  and LibreOffice runs an Ask forum here: https://ask.libreoffice.org/en/questions/

Unfortunately the Apache OpenOffice Accessibility documentation was not updated following implementation of IAccessible2 support and still refers to MSAA support via Java Accessibility and the Java Accessibility Bridge.  However a vibrant user forum is still available to assist here: https://forum.openoffice.org/en/forum/index.php

Stuart