SFTMIME.EXE is one of the two primary command line utilities you will find yourself using to programattically control App-V. SFTTRAY.EXE being the other.
SFTMIME's main purpose is controlling the client, as where SFTTRAY's main purpose is launching applications. It goes beyond that but in a nutshell those are their jobs.
One problem you may see with SFTMIME is a lack of response. In this instance REFRESH SERVER, when when used with /log provides no response unless there is an error. Most people go into the Client Console and refresh to see if the server status changes to "Ongoing", and if it doesn't change assume it didn't work. The only way to ensure it kicked off a refresh is to check C:\ProgramData\Microsoft\Application Virtualizaton Client\sftlog.txt
If you see it cycling in the log, you know it worked. This doesn't do wonder for programattically checking, as even looking at the modified date of sftlo.txt doesn't tell you anything other than SOMETHING happened. You have to actually parse the log file to get a clear result.
If you intend to run SFTMIME via scripts or something like SCCM don't forget to specify /LOG <pathname> otherwise if it fails, you are left to scratch your head and wonder why.