Maybe it doesn't work in Linux,
but LO's 'Find-Replace' works with multiple documents for me;
[still with 3.4 ]
The only thing that never worked is the 'Find', for some reason
I'll click on that one by mistake at times, only to have the
document sit doing nothing ...
then I click on the Find-Replace and can find, or whatever, fine
Was this a bug back-then or what?