Optional properties don't change language-dependent displayed text. Do the following:
1. Set your language preferences to English.
2. Go to Resource and edit the details
3. Expand optional properties. Note that properties and optional properties title are both in English.
4. Set your language preferences to Spanish (or any other language)
5. Go to Resource and expand once again optional properties.
You will note that the title is still in English, as they are resource metadata (optional properties). They should be in the preferred language (that last you have chosen).
I attach the patch for 2-6-x.