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Traiteur, Tracteur, Trakteur  = Stadtkoch, Speisewirt - city cook, dining host

Midwife is Zöhrmann

You must search in Ukraine not in present days Austria, which has nothing to do with that area NOW. The files still in the Ukrainian area and not at former rulers which not longer exist (Empire).
Search also at Galicia Genealogy Boards via google.
Sometimes also special Links for special areas.

https://en.wikipedia.org/wiki/Galicia_(Eastern_Europe)
https://de.wikipedia.org/wiki/Galizien
https://www.geshergalicia.org/galician-town-locator/

People for professional Ukraine Genealogy:
http://www.ukrgenealogy.com

What do you mean with Bostu district? Never heard for the former Austro-Hungarian Crownland Galizien und Lodomerien (Galicia). Look if you can find it here, to clear that up (Bezirk = district): https://de.wikipedia.org/wiki/Verwaltungsgliederung_Galiziens
Judicial districts: https://de.wikipedia.org/wiki/Liste_der_Gerichtsbezirke_in_Galizien_und_Lodomerien

Example birth Josef Kaminsky.
In this parish most books for only one year. The index to look through names A-Z always on end of right side pages -> index.....for Josef it says his entry is in same book page 152 (page in BOOK not right side list).
Index: http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/01-116/?pg=245
Entry: http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/01-116/?pg=155
But Hernals has the birth index also here extra by years: http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/?page=7#register-header

For his brother you have to search at year 1912:
Hernals books list: http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/?page=3#register-header
There are two 1912 books (no idea why), both have no index (again no idea why).
http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/01-105/?pg=1
http://data.matricula-online.eu/de/oesterreich/wien/17-hernals/01-106/?pg=1
As you know his birthdate you can search in the book by date, a little tedious. I remember that I looked for him and could not find. So you may look also again at this Hernals.....it is more difficult as they wrote (listed) after baptism date, so some birth dates are later or earlier.

Maybe overlooked or the other children born another place? Marriage happened in Lichtenthal, so possible also baptisms there. I do just not remember if I made also look up at the births for Lichtenthal. Index books for Taufen/ baptisms end 1901. So also to search via birth date in books directly.
1912: http://data.matricula-online.eu/de/oesterreich/wien/09-lichtental/01-59/?pg=1
1915: http://data.matricula-online.eu/de/oesterreich/wien/09-lichtental/01-62/?pg=1

Hope you can find Karl and Franz, maybe also Adele in Lichtenthal or Hernals.

Klášterský Mlýn (Klostermühle) in Czech Rep. belonges to Rejštejn (deutsch Unterreichenstein) close on the border to Bavaria.

https://de.wikipedia.org/wiki/Rejštejn (copy Link into Linkadress, it does not work)
Klostermühle is north east of Flattnitzhütte, Oberkreuzberg, Spiegelau about the BORDER (very close)!
Copy this into google maps, does also not work, assume because of the Czech letters: Klášterský Mlýn, 341 92 Rejštejn, Tschechien

  Ok and HERE the history to the LÖTZ family with their glass work in Bohemia. You may copy it into google translator. The first sentences: "The Bohemian glass industry has always been at the top of the world. Their products have won numerous awards and are in demand in many countries. Incidentally, the founder of the world-famous Swarowski company also came from Bohemia. At the turn of the 19th and 20th centuries, however, another Bohemian glass factory conquered the world market: the Lötz company from the Bohemian Forest. Although the company went under after the Second World War, its products are still valued by experts." https://www.radio.cz/de/rubrik/panorama/edles-glas-aus-dem-boehmerwald-die-geschichte-der-firma-loetz

I´m not sure about the realtionship of all within the Lötz glassmaker family....Mathilde´s parents were Johann Lötz and Crescent(ia) Krieger. I`m more then confused who-is-who. 

Johann Lötz, * 19.4.1778 Wassersuppen, district Taus (Böhmen), † 17.3.1844 Annathal district Schüttenhofen, Bohemia (now Czech rep.). (catholic) (possible grandfather of Mathilde born 1865?)

https://www.deutsche-biographie.de/sfz53846.html

It was once one of the most important glass factories of the former empire: the Johann Lötz Witwe company, founded in 1851 in Klostermühle in the former Bohemia.
What a strange name!
It comes from Johann Lötz, a famous glassmaker in the region who bought the oldest glassworks in Wottawattal in Bohemia in 1850, but the actual operators were his wife and widow Susanne Lötz and his grandson Max von Spaun.
https://imkinsky.com/?cpt-article=loetz-1900

Birth of Adele Lötz March 13, 1895, Parish church Lichtenthal, Vienna 9th district
died Aug 23, 1941, Standesamt Hernals, No 375/41
Mother: Mathilda Helena Lötz, handworker, cath., born Flanitzhütte, parish Oberkreuzberg, legitimate daughter of Johan Lötz and Crescentia Krieger
http://data.matricula-online.eu/de/oesterreich/wien/09-lichtental/01-44/?pg=44

https://de.wikipedia.org/wiki/Lichtentaler_Pfarrkirche

Flanitzhütte belonges like Oberkreuzberg to Spiegelau, Bavaria, Germany:
https://de.wikipedia.org/wiki/Spiegelau#Gemeindegliederung
https://en.wikipedia.org/wiki/Oberkreuzberg
https://www.bistum-passau.de/kirche/6155/pfarrkirche-oberkreuzberg
https://www.google.at/maps/place/Nordwald-Zendo/@48.9059742,12.8236245,10.98z/data=!4m5!3m4!1s0x0:0x5a663585c2c9ecc4!8m2!3d48.9567291!4d13.2996503

Church books online: http://data.matricula-online.eu/de/deutschland/passau/oberkreuzberg/