It should be safe to shoot.
Although the overall quality of guns made in India leave a lot to be desired, if you use sensible powder loads similar to the loads that were typically used in flintlock military pistols you shouldn't have any problems.
As your pistol is listed as being a .64 caliber gun, Dixie Gun Works catalog shows a similar .67 caliber flintlock pistol using a 35 grain powder charge . A smaller powder charge of 25 grains would also work quite well. (A empty cartridge case can be used as a powder measure. For instance, a empty .357 case will hold about 27 grains, a empty .45 auto case holds about 26 grains and a empty .44 Colt cartridge case holds about 35 grains.)
Speaking of powder, flintlocks need to be loaded with real black powder. The synthetic black powders like Pyrodex or 777 work poorly or not at all.
You should use a slightly undersize lead ball in your gun. This should be patched with a tight weave cotton patch large enough to cover the ball in the area where the ball will meet the bore.
Looking at Track of the Wolf's selection of ammunition I see they have .610 or a .626 diameter balls for sale. Either of these would be suitable for your pistol. The thickness of the cloth patch for the .626 diameter ball should be .010 to .012 thick.
https://www.trackofthewolf.com/List/Item.aspx/127/3