The JOS doesn't say much on synastry good or bad. So you will kind of have to learn the meaning of planets and their energies mixed with the sign they are in and put two and two together.
For example Saturn Conjunct Venus in Sagittarius is going to be different than Saturn conjunct Venus in Virgo in the theme and how this plays out. This particular configuration is a nightmare btw I am going to talk a little about it cause I share this one with my partner. All it says on the JOS is that the Saturn person rejects the venus person. The reason though is whatever your Saturn issue is it somehow gets intertwined in the relationship and it could be an issue or person represented by the Saturn position that ends the relationship. The Saturn person sees it as serious and some deep wound of some kind the venus person sees it as something not that big of a deal or is playful about the issue.
It is possible to work through this one but not easy. Probably something most people should avoid.
The other one Mars Conjunct Saturn it just simply says the two antagonize each other that's all.
Doesn't go into much detail I had this with someone close to exact when I was younger.
This makes it feel like the people are hostile to each other on some deep level. The Saturn person feels attacked or wounded in some way.
The Saturn person would rather kind of avoid what Mars is fighting for or has insecurities about it. In this case it's likely both people take these issues really serious unlike Saturn venus but its more a fight they somehow are on opposing sides.
I think more needs to be said about a lot on there. I know the energies of things and how some of this plays out. I mean it's not the same all the time I know but general descriptions could give people ideas for what to look for in it and they could look into it further.