I would have a reputable fiberglass shop look at your transom. If you can determine they are only spider cracks in the gel coat, with no structural damage to the transom or hull, then you will be fine. If there is damage, the cost of the repair may make the price of the boat vs value too far off balance. Never had a transom repaired, but from what I understand, it ain’t cheap. If you could repair it yourself you would save money. Best of luck!
Don