Yes definitely the risk you take buying offshore. If my main needed altering I would have very sheepishly had to ask someone local to fix it. In saying that if you follow the very very detailed instructions from the crowd I got mine from then you will get what you want.
Most important. A guy at Great Barrier had his new furling jib delivered recently, exactly to his dimensions. Sadly not including space for the roller-furler. By the time he gets it re-cut by a local it's going to look awful and cost more than the local product.
Admittedly, at the price point I was buying at it didn't carry a lot of financial risk so was well worth a punt. Paying 2.5 times more to buy local for what I am doing was never going to be justified. If I was racing or planning on keeping the yacht super long term I probably would have gone local. Horses for courses