Yes, chinchillas can safely eat salad only if in a smaller quantity and only certain types of salads.
If a chinchilla was to eat salad in a large amount they may get sick and get an upset stomach so make sure to not overfeed salad to your chinchilla.
Some salads such as fruit salads may include fruits that are high in acidic content which is bad for a chinchilla and therefore should be avoided.
Acidic content will cause a chinchilla to have digestive problems and therefore should be avoid.
Therefore if you are unsure of which types of salad is safe for your chinchilla it is better to avoid feeding your chinchilla salad all together.
It isn’t the ideal food for your chinchilla and therefore there are better options for food to feed to your chinchilla.