I suppose I understand this, but based on the history of geometry this isn't entirely true.
History of geometry - Wikipedia
Geometry, next to arithmetic is a very practical area of mathematics. It is used or useful practically everywhere. While 3% off might be alright, it does indicate the principles are there and being used. They will improve with time. Some of the more crucial theories, such as Pythagorean Theorem were likely developed for the construction of large stone works.
I will remind you that getting them to develop pi would be a coup on par with our iron working. Exact just isn't possible without it anyway.
If our people can get by building a dam without some sort of understanding of geometry I would be massively surprised