Oracle Data Modeler: unable to create Java instance

The following error was displayed during the start of Oracle SQL Developer Data Modeler (v3.3.0.734) on Windows:

Unable to create an instance of the Java Virtual Machine
Located at path: ..\..\jdk\jre\bin\client\jvm.dll

This could be fixed by editing the file datamodeler\bin\datamodeler.conf :
try to change the following line
AddVMOption -Xmx768M
to
AddVMOption -Xmx512M

and restart Data Modeler after this.

Oracle Data Modeler: change user interface language

Oracle Data Modeler in the current version (3.3.0.x) does not allow to change the user interface language in “Options” or somewhere else in the GUI.

However, it’s possible to force it to switch to some other language, using datamodeler\bin\datamodeler.conf configuration file.
The following lines should be added to the file for English:

AddVMOption -Duser.language=en
AddVMOption -Duser.country=US