I accidentally stumbled upon this page, and couldn't resist the temptation to give it a try.
Here is my interpretation. The handwriting is really old-fashioned and hard to read, but I think I figured out most of it. I've left a few unintelligible words blank, but as a whole the postcard makes sense.
Swedish text (with line breaks the same as in the original)
Mårbacka den 5 Aug 1929.
Kära Moster! Länge sedan
vi hörde något från Er.
Mamma o jag har varit här
på Mårbacka en hel mån
nu men skall resa om några
dagar hälsar då på Moster
Betty i Göteborg på hem-
vägen. Här är så härligt
och skönt. Roligt komma
ut på landet och njuta
av skogsluften. Mamma
har varit så ... denna
tiden så jag tror att det
gjort henne mycket gott
Hon sänder sin hjärtliga
hälsning. Hjärtliga hälsningar
till alla Mosters ... Elin
My translation into English follows:
Mårbacka (a small town in Värmland), August 5th 1929
Dear (maternal) aunt! Long since we heard anything from You. Mother and I have been here
at Mårbacka for a whole month now but will travel in a few days. Will then visit (maternal) aunt Betty in Gothenburg on our way home. Here it is lovely and nice. Nice to get out into the country and enjoy the forest air. Mother has been so ... all this time, so I think it has done her a lot of good. She sends her sincerest regard. Sincere regards to all of Aunt's ... Elin