I have a recipe for mango chutney. Besides the mango, the ingredients are apple cider vinegar, onion, red bell pepper, and various spices. The recipe makes quite a bit, and I don't know if it would would be freezable? Thoughts?
There's generally no "safety" issues with freezing anything (provided your freezer is sufficiently cold and stays that way). Freezing is very good for preserving all sorts of food for indefinite amounts of time. The main problem with freezing is loss of quality - loss of moisture (freezer burn) and cell expansion are your main issues. Neither of these make the food unsafe to eat.
Uncooked, fresh, high-water produce (strawberries, spinach, peppers, etc) come out of the freezer with a different texture because the cells of the produce expand as the water in them freezes and are destroyed, so when removed from the freezer, their texture has changed significantly. The same thing happens when they're cooked so, as long as your plan is to cook them afterwards or they are already cooked when they go into the freezer, the end result shouldn't suffer. Many recipes for fruit cobblers/pies actually call for frozen fruit (particularly blueberries) because there's generally little noticeable difference between the final products when using fresh or frozen produce.
I don't see anything in your recipe that should be problematic. As the whole thing is already cooked, it should be similar to freezing pasta sauce - it will defrost in pretty much the same condition as it was frozen.
As I noted in a comment, I find mango freezes quite well, regardless. I buy it frozen in chunks and eat them as a treat/snack all of the time. The flavor is still great and I don't have to struggle with peeling and pitting the fruit or worry about it going bad before I get to it.
Chutney as we know it in the British Commonwealth is a vinegar based sauce. This means that the vinegar introduces enough acidity into the environment that spoilage bacteria is unlikely to grow. You mention that your sauce has vinegar in, so I believe this to be the case
The vinegar in the sauce is likely to have the effect of pickling the mango in a similar manner as the devil eggs that yous sometimes see in bars are pickled.