First you have to shutdown your SQLDEveloper.
Edit the file sqldeveloper.conf for changing the IDE language adding the following lines:
# Tomeu Mir – forcing English UI language
The location of the sqldeveloper.conf is at /Applications/SQLDeveloper.app/Contents/Resources/sqldeveloper/sqldeveloper/bin
IDE Font Size
Edit the file ide.properties for setting the desired font size of the IDE. Comment any line like Ide.FontSize.* and add the following one:
For finding the location of the ide.property file you can do the following from a shell command and choose the one corresponding to the highest edition.
$ cd ~/.sqldeveloper/
.sqldeveloper$ find . -name “ide.properties”
Now you can restart your SQLDeveloper and enjoy working again.