Hey, someone asked about my project! First time on this site…
Anyway, the current state of affairs on Windows is that the SIL converters installer has not been updated to 64-bit yet. The code has been updated, but a new installer needs to be built.
To get it to work, one solution is to go back to a 32-bit version of LibreOffice. The latest version of LibreOffice can still be downloaded as 32-bit.
However, it may be better to use newer versions instead. Install FieldWorks 9, which contains a 64-bit build of the SIL Converters core. You may need to uninstall the SIL Converters application so that it doesn’t conflict with the newer libraries in FieldWorks.
if they somehow need to be uploaded into LibreOffice?
No, the LingTools add-on uses the same encoding converters as FieldWorks or SIL Converters.
EDIT 2020-06-01:
The code has been updated.
The encoding converters core has been updated. However, there is a different repository for the applications (Clipboard Converter, Bulk Converter et cetera), and that code has not been updated yet. The installer also needs to be updated, as mentioned above.