The 11.1.2.3 metadata editor can be used to edit 11.2 metadata as long as it's installed on a supported platform. The same applies for HFM 11.1.2.4.
An HFM metadata editor that supports newer platforms 11.2.x is on the road-map from Oracle
The HFM client 11.1.2.3 can be found in the Oracle Software Delivery Cloud.
Search for "Oracle Enterprise Performance Management System - Client Installers 11.1.2.4.900" and select platform Microsoft Windows (either 32 or 64 bit, the package is the same).
Then download the file V975630-01.zip.
Specifically, the version of the HFM client in that package is 11.1.2.3.502.
Note: if you open the HFM client and go to Help > About, it will reflect the version of the HFM server installed on the same host. Regardless of that, the actual version of the HFM client is still 11.1.2.3.502.