I am sorry for the delay. Unfortunately, sometimes an answer gets lost when a customer sends in a second reply without getting an answer for the first. I'm terribly sorry about that and of course will start over right now.
If the executor simply had to provide further forms and did so this is not necessarily the executor's fault. Presumably the executor filed a terminal return within six months of the death of your mother. That is required. But, there's no way of knowing what the CRA was doing with the return. As the CRA asked for more forms presumably either your aunt made an error or the situation was more complicated than it first appeared.
The executor cannot speed up the receipt of the tax clearance certificate. Thatvcomes from the CRA. It is not something that your aunt can simply file.
Usually waiting for tax clearance is one of the main reasons why an estate cannot be wound up. So unless you really believe your aunt is lying it seems that your best step really at this point is simply to wait for a short while.
One concern I have is that you said that the money that is in estate is not earning interest. That is not prudent of course and your aunt should have put that money in a safe investment that was earning some interest.
If you feel that you being ignored you should write to the executor or the lawyer if there is one or else retain a lawyer to do so for you.
However, you should be mindful of doing that because anytime legal fees are spent some of them are spent by the estate and this will reduce what you'll get.
I know that not the answer you're really helping hoping for but I'm trying to provide you with a realistic approach so that you don't end up using up a lot of the funds in the estate dealing with your aunt.
However, if you really don't truste her your next step really should be to apply to the court to have her removed as executor and have you or some other beneficiary appointed in her place.
Does that help a bit?