Best way, I do things:

I take frozen block, cut sections, and place an empty plastic slide box on dry ice in a styroform box near me, as I cut slide, I assess under a microscope near me, if slide has the right section and I record it, I store the slide in the slide box which is at dry ice. At the end I store the slide box at -70 or -86C whatever is available. You may take out slide from -70C slide box when you want your experiment.

In your case storing at room temperature, slides are no good anymore, in my opinion. You may start cutting sections again and store slides at -70C as I mention. Also never store frozen tissue at Room temperature even briefly,

Have you fixed/preserved these sections in some way ? If not, they will likely be totally degraded by now. If yes, they might still be affected by ambient RT conditions (drying, surface contamination, etc...). In general, I would think it best to keep frozen sections frozen until use. But as with anything tissue-based, you won't know unless you test it.