Hi Teemu,
The simplest way to see offbeats in a 4/4 rhythm like Sofa is simply to call the odd numbered beats (1, 3, 5 ... ) downbeats and the ones in between (2, 4, 6 ... ) offbeats.

I was just about to post to this community about a new book of mine that explores this very topic of offbeats, as one of the lessons. The book is Roots Jam 3: Arrangements for West African Drum & Dance. See djemberhythms.com/roots.htm for details.

happy drumming,
Nowick

This is a very interesting question. The notion of downbeats & offbeats/upbeats has been a source of endless fascination for me in West African rhythms. As far as I can tell from playing with Africans, it just doesn't seem they feel downbeats & offbeats in the same way I do, based on my Westernized sense of pulse. It seems that Africans just feel every note in a rhythm as part of "the beat." Whereas for me, my kinesthetic sense of downbeat is crucial to keeping my place in the rhythm, much to my consternation when trying to play Dununba rhythms when the dununs are mostly playing "offbeats." I've been playing djembe along with Dununba rhythms for many years, & *still* I get thrown off sometimes. In 6/8 rhythms, trying to play just the second & third notes of the triplets without the "downbeat" is so much harder for me than if I'm playing the downbeat, but when I play with Africans, it doesn't seem to be any problem for them. In fact, it seems they are a little puzzled when non-Africans like me struggle with something that just seems straightforward to them.

So my suggestion would be to not really worry about what's a downbeat or offbeat & just think of every rhythm as having its own beat. Just try to learn to feel that beat, & you should be fine.