In the LanguageTool-3.1.zip for sk-language in the file filter_lft.py used a wrong format of print command for the Python 3.* :
print (form, lemma, ntag, sep='\t')
If the target-PC has Python 3.* installed (it was by me the case) - the python error message being produced, which might confuse in case of some other error (like "Could not create java implementation loader") occuring after that.
Please fix the format of print command or disable the print message there at all.
By the way - the "Could not create java implementation loader" problem on Win7 64 bit with OpenOffice 4.1.2 was solved by:
1) Installing the 32-bit version of Java JRE (currently 8.66).
2) Changing the system-path to match first the 32-bit version of JAVA
3) In the Control-Panel->Java->Java->View->was found location of 32-bit JAVA-version to ensure it's listed there.
4) In the OpenOffice Writer -> Settings -> Java was selected the new listed 32-bit version of the JAVA.
5) Restarted the OpenOffice Writer and installed the LanguageTool extension using the Extension Manager.