Hi Ian,
I was unable to find a birth record for Magareta Cathrina Svedberg either.
I don't know for sure if Gustaf was the father but I am making a reasonable assumption. I'm sorry, when I said brother I meant Gustaf Emil's brother Carl George. There were 3 Tillanders that were in Borås during the 1842-1844 time period according to Husförhörslängder, Inflyttning and Utflyttning records.
August Tillander born 9/21/18
Gustaf Emil Tillander born 9/9/18 and his brother Carl Geo born 5/25/1826
Does this record show them in the same house 459/460?
https://sok.riksarkivet.se/bildvisning/C0043134_00057Again thanks for all of your help!
Roger