Try starting a completely new project and building your data model there.
Before you create the project, use one of the methods I've mentioned to make your DBMS the default for databases.
Now to the problem of Java. This is sort of related, but not the same problem. What's happening here is that EA is reverting to the default code generation language. This is a different setting in EA. EA stores the code (versus database) language in each project. Sounds OK at first, but there's a catch.
I'm going to go through this in detail, so please bear with me...
When you create a new project, EA actually creates a copy of a 'seed' project and stores it to the folder and file name you select. An analogous process is used for projects in DBMS repositories, in that EA requires that you copy the 'seed' data via a project transfer.
Whenever you create a new project it will inherit the code language setting from the seed project you used. If the seed project has a different default code language than you want, you'll need to change that setting every time you create a new project. More importantly, any pre-existing packages and elements will still have the previous setting, and would also have to be edited.
You can designate your seed project if you create a new project by clicking the Copy a Base Project link on the EA start page. However, this project would have to have the language set to your desired product or you'll have to go through the above hassle.
If you don't designate your own seed project, EA copies the EABase.EAP that is kept in your EA installation folder. This file is empty - it contains no packages or elements - but it does have a default code language set. The default setting is Java, which is propagated to all project files created from this seed. That is what's causing your problem.
You can get around this by editing EABase.EAP. If you change the code generation language (via the Tools | Options | Source Code Engineering dialog) and save the file, the new setting will be the default inherited by all new projects.
You could also make several seed projects - each a copy of EABase.EAP - and set them to different languages. You might also set other options to reflect common configurations in your shop. Then you can use the Copy a Base Project link to use one of these files as a project template. You can also use one of them as the source for the initial Project Transfer for a new DBMS repository.
In any case, make sure you start with a clean project set to default to both your DBMS product and code language.
HTH, David