Fairly good looking mainsail.
Here's what I see, 2 possible 'problems'
1. the smaller diagonal wrinkles near the luff indicate that probably the sail is raised without sufficient luff tension. Go back to my previous post about properly raising a dacron main. When you do this the leech will also become a bit more flatter instead of the light curvature towards the weather side.
When you check the tack angle - the angle that the the top of the boom makes with the mast - when the sail is properly raised and if you can measure that angle precisely - the tack angle for a T30 should be 88° .... with the sail properly 'stretched out' as described in that link in my previous posting.
2. the large horizontal crease (a sailmaker will call this a 'girt') ... may be the result of someone routinely not releasing the outhaul tension when the sail was being stored on the boom .... and after dropping the sail, used the topping lift to raise the end of the boom away from the cockpit. (Most non-racers set their outhaul tension and leave it that way ... all season long !!!!!! ... very bad for sail life). Alternatively, There's probably a mast track slug at the forward end of this girt; and, Id suggest that the binding/webbing or shackle that attaches the slug to the sail is too tight and needs to be made 'longer' probably because the tack connection to boom is located further back from the gooseneck than normal (sailmaker didnt correct for this difference and probably never physically was on-board the boat to take measurements). Girts such as these are a common problem ... but NOT releasing the outhaul tension can lead to serious permanent sail deformation.
Other 2a. ... I may be seeing a small 'cringle' on the main just above the tack/gooseneck. I dont see any hardware for a 'cunningham' - a small diameter line that goes through this cringle and additionally pulls the luff (boltrope-sleeve) 'down'. If a 'cunningham' was routinely used on this mainsail, especially used with a lot of force and over a long time, that too will eventually lead to such permanent 'stretch' in a localized area and produce such a 'girt'.
Horizontal (or vertical) girts such as this is not a serious sail problem at all, it just means that the sail is not tensioned equally from one of the 'corners'. I'll make the bet if this sail is properly raised so that the luff becomes better tensioned, most of this girt may lessen or disappear.
Rx- If your eyes are glazed over by this expansive explanation, start with my above previous post and follow that link about 'properly raising' to make your 'on the water' evaluation ... If you do this evaluation etc., possibly all the minor problems I see from your pic will simply disappear.
Your pic show a quite 'decent' sail.
Woven dacron sails rarely become 'blown out'; but, you do have to stretch them out when raising so that they take their proper as-designed shape.
;-)