This may be a bit mundane but I cannot help wondering whether someone has mixed up either profession with residence, or the last place he stayed at was a (relative's?)shop. In German "Kolonial waren" were groceries of the more exotic type, i.e. imported from the "colonies". A "Kolonialgeschaeft" would be a grocer's shop, "Kolonialhandel" grocer's trade. As "Laden" und "Geschaeft" can both mean shop may be "Kolonial Laden" was the term they used locally. Just a suggestion - of course if you have found it to be a place a completely useless one! Good luck anyway.