Short answer: They're probably not safe.
Unlike "microwave safety", there isn't a safety risk in contaminating the food contents of the jars due to heating in an oven; in this case you just run the risk of the jars breaking.
I am not sure what the symbols on the bottom of your jar mean; (see edit below) from what I understand—unlike plastic resin identification codes—there isn't a standard set of symbols for glass. Those symbols likely represent the manufacturer, production date, and patents.
Unless glass is processed in a special way, it is prone to breaking when it goes through rapid temperature changes. Therefore, if your glass is run-of-the-mill soda-lime glass (which is extremely likely), and if you were to put it from room temperature directly into a 450°F oven, the shock of that rapid temperature change would likely crack it. Furthermore, even if you were able to gradually heat it up to 450°F without it cracking, it would likely crack even as it naturally cools down. In order to try and ensure that the glass doesn't crack you'd have to both gradually heat the jars up and then very gradually step the oven temperature back down to room temperature.
If you want to use glass, your best bet would be to use something like Pyrex.
Even Pyrex, which is explicitly designed to be oven safe, can't withstand the direct heat of a broiler, though.
Edit: I believe the symbol on the bottom of your jars reads "A.G.C." surrounded by the outline of the state of Arkansas. This implies that your jars were made by the Arkansas Glass Container Company. I believe the numbers indicate the model number, which appears to be this jar. AGC unfortunately don't have anything on their website listing the oven safety of their glass. If you're really interested, you could try contacting the manufacturer.
I would start by rolling the pastry dough thinner; I often have my dough too thick the first time or two that I work with a recipe. Keep the dough cold to make it easier to work with.
Next, I would try different oven times and temperatures. Try a temperature 25-50 degrees (F) higher, and pull the rolls out 30 seconds to one minute sooner. The nice thing about playing with oven times and temps is that you can go through many tests quickly by just putting a few of the items in for each time/temp combination. (Extra mass in the oven, such as a pizza stone or even some bricks, will help keep the oven temp more steady.)
If the outside of your rolls are getting over done before the inside is done, try chilling the rolls in the refrigerator for 30 minutes or so before baking.
Best Answer
It will firm up a little bit during chilling, but not much. It is certainly supposed to be firm enough to keep its shape on its own when taken out.
If you have baked creme caramel or cheesecake, then try to get it to a similar consistency as these. If you haven't, you may want to use a roast thermometer. The final temperature (assuming a traditional flan without starch or flour) should fall in the 85-90 Celsius range.