I don’t think that is the issue. I think it is maybe when you are trying to get the input values out. You should create lists to store the values, and run the workflow event when an inputs value is changed to use the inputs value to add to your list of values.
I don’t see why it is possible or not possible based on the type of data in the RG, but rather difficult to reference an inputs value that is inside of the RG using the click of an element that is outside of the RG.
If you had a button in the cell where the user makes those input values that would be clicked to capture the input values, it would be possible because that button would be in the RG cell. Since you wouldn’t want that then the only way to capture those values on an individual basis is when the input elements value is changed.
As it would be likely the user will make changes to those values or delete a room you will need way to store those values on the page and not use the database until the user actually clicks DONE to confirm.
I think you might find the List Shifter plugin a handy way to store those lists and to operate on those lists in different ways.