Is it obligatory to wash the prayer rug or bedsheet if it has been touched by wet impurities from a baby girl's diaper, but no trace of that wetness is visible on the prayer rug or bedsheet?

If wet impurity affects a child's clothes or a carpet, then if its trace is visible, the affected area is washed. If its trace is not visible, it is not deemed impure. If the wet impurity dries and its trace disappears, then the place becomes pure by that, especially if it was a small amount. It is preferable to promptly purify the defiled place with water, and it is sufficient to wash only the impure spot.