You will need to modify the geometrie GML to include the srsDimension attribute on every poslist node. After that, you can load the GML into pygml and transform accurately to WGS84/EPSG:4326.
Example code:
from pyproj import Transformer
from shapely.geometry import shape
from shapely.ops import transform
import pygml
transformer = Transformer.from_crs('EPSG:28992', 'EPSG:4326', always_xy=True)
transform(transformer.transform,shape(pygml.parse(obj['geometrie']).__geo_interface__)).wkt
You will need to modify the geometrie GML to include the srsDimension attribute on every poslist node. After that, you can load the GML into pygml and transform accurately to WGS84/EPSG:4326.
Example code: