Sorry but your save is from 2047 AD, I am not going to investigate that. If you see any issues in the regular game time period, let me know.
How do you mean? It's not just a convenience thing, because usually GPs discover two techs at once and you get locked out of a more advanced second tech the way things currently work.
Let's assume you have Steel but lack Architecture and Artisanry. Then a Great Engineer would give you Architecture first, and Artisanry second. What this rule ignores is that once you have Architecture, you can also research Fortification, which can also be discovered by a Great Engineer. So Fortification should be the second tech you get.
Usually getting research into later techs is more valuable and desirable, both because they are more likely ahead of the curve and also because there is less of a chance of overflow research getting lost.