Could you please clarify what exactly do you mean by "Before the Indexes value was available in the ISearchFilterable, but now it isn't." The interface is still there and it was not changed. I have checked the description of the interface and there should not be any index value.
Could you please try to describe the issue in more detail? Maybe provide some code snippet? What exactly are you trying to achieve? Could you please clarify what was working before and what is not working at the moment?
Best Regards, Roman Konicek