Cold is generally good. Anyplace between 40-65 °F is good in a root cellar. However, there’s some foods we’d often rather not let freeze. Naturally, these would be our high-moisture content foods in storage.
The reason for this is that freezing mechanically breaks down fibers in food or other glutinous or lipidic structures that give food it’s texture and it’s cellular integrity. It breaks down cells which are little puddles of biology surrounded by membranes that ideally keep the stuff inside in and the stuff outside out. Breaking down these fibers and barriers makes the food itself more susceptible to penetration by nasty organisms. This breakdown happens all the way down to the chemical level as we see conventionally frozen foods loose some nutritional value. Repeated freezing and thawing just makes the damage happen again and again.
Freezers in general I don’t really consider to be long term unless it’s always frozen where you are. I try to keep the engineering low-tech, on the off-grid or off-gridable. Where I live, all that freezes will one day thaw.
Probably the best research that anybody has ever done and actually shared it with the world are the folks at Walton Feed. Their information was put together by true experts and has evolved over the years into a series of charts. Now charts are great for condensing information but all the richness of the stories has been sanitized away. But feast your eyes and brain on this. This really tells you how not just temperature but the right temperature at STABLE LEVELS really makes or breaks you. And how the label or the guarantee of “shelf life” really don’t mean squat in terms of our traditional methods. And we see how even one day of super-heat can really screw canned food contents. But don’t despair. Don’t give up if your treasured preserved overheated for a day or a week, keep every practice here going, don’t stop, “long-term” in survival terms means one more day. For us humans, survival in the basest terms means eyes-open tomorrow. Keep thinking “every trick in the book”.