There are many things associated with the Ministry of the Sick to hospitals and nursing homes that are outside of the normal operations of the church. That is what Diocesan training is for. If you church is not training you properly that is the fault of your parish.
Also many things will happen in the ministry that they can never prepare you for and you will have to think on your feet. Knowing the church policies and diocesan polices and making sure that whatever you do is in the spirit of the policies is what is important.
As with your above statement, I would think that the Vatican or USCCB would have addressed this. If nothing else, I would expect a statement that these matters are addressed by the local diocese.
You are expecting the church to be like a lawyers office having policies for EVERY situation and what you should do in every situation. There are situations that are not specifically addressed by the Vatican or USCCB and are just passed on through training.
Honestly, in a situation where you can’t return the hosts to the Tabernacle, what do you expect to do with the hosts? Keep them until you can? Where would you keep them? Do you think your house is worthy of keeping them? Should you keep them on you until you can? The only valid option is to consume them.
Incidentally, it’s never a problem to return the hosts to the Church. There are several hours to do this after leaving the nursing home. It it strictly a matter of convenience for the EMHCs to consume them.
If this is the case then it is an issue that should be taken up with the pastor. Doing it just for convenience isn’t a good reason. There may be good reasons (i.e. the nursing home can only see you at a time that makes it impossible to return the hosts while the tabernacle is accessable.)
Asking for more training is a good thing. Even when you are done the training questions will come up. When I doubt about a sitatution I always talk to one of the priests in the parish to make sure I did the right thing. When you know all the official policies and understand the “spirit” of the policies you can usually figure out what is the right thing to do.