Apparently, you found some useful data on other boards. You should keep us informed of what you hear, so that work is not repeated for no reason.
It appears that the focus of your search is now Kollerschlag in Upper Austria which includes a village called Haselbach. Kollerschlag is in the district of Rohrbach, very close to the border to Germany/Bavaria. The nearest town in Bavaria is Wegscheid. A google search comes up with a medical doctor with name Barbara Christl in Wegscheid. Perhaps you should contact her. There is also an Ellis Island record for Rudolph Christl, carpenter, who arrived in 1910 coming from Haselbach. He left his wife Franziska behind in Haselbach near Kollerschlag.
You need to find out where (in 1900) the parish was for Haselbach. The obvious candidate is Kollerschlag, but it could also possibly be in Sarleinsbach or Peilstein. The problem with the online parish records is that any book which includes data fron the 1900s seems to be barred fron access (due to privacy law).