A case going to a technical adviser is not a standard stage in the process. A technical adviser is a senior official who is able to look over cases where either there is some unusual feature about the application, or where the processing seems to have gone wrong in some way. The TA has more knowledge and more authority to interpret the rules than ordinary COs.
So I think it's a cause for cautious optimism that your case has been referred to one. But on the other hand, there isn't any way to tell how long s/he will take to deal with things. We don't know how far the COs who previously worked on your case had got, so there may still be some checking to be done - answers to wait for, and so on.