I actually wanted to install again but the "Change" and "Repair" options are grayed out and the only possible option is "Remove". Following your suggestion " just manually remove the strawberry installation" I removed the installation directory - "Change" and "Repair" are still grayed out but I can uninstall via Control Panel - Programs. The uninstall seems to succeed although it doesn’t remove the settings from the registry. Now I can install again.

As for the UI language issue, I found out that it is determined on initiation of the UI and not during installation. When I open the UI it checks the "Formats" ?!? name in 'Regional and Language settings' and sets the UI language accordingly.