That GetSpline method not being dll exported should not have anything to to do with the change where we move dllexport from type to methods/static vars.
The large scripted change should not remove dll export on anything that was previously exported. It was made to fix the issue where lots of (especially implicitly generated) functions/staticvar were _both_ inline and having dllstorage. This caused issues internally with some of our new ways of building code and had to be addressed.
If there were removed dllstorage somewhere that was unintentional and should be fixed, please report those and I apologize in advance.