I have lots of thoughts about this as well, especially because I'm one of the bad language partners (especially when the partner is in another time zone). I feel like language partners are most useful when you're both at quite a high level, but the most important thing is that they are willing to be patient with you and you are willing to be patient with them and actually conduct language exchange rather than just focus on improving your own language. For German, which is the only foreign language I can converse in, many native speakers already know English and thus I cannot provide anything for a language exchange, so I'm grateful I have the financial means to pay for some conversational practise. Additionally, I have a friend who is a native German who speaks with me in German, but at that point it's not language exchange, it's just a friend who happens to speak your target language HAHA. You're lucky in that you speak "rarer" languages, so perhaps a language exchange is still possible. I haven't tried this yet (but once I FINALLY submit my essays) I'll be suggesting to my language partners for Chinese that we set aside a specific time to concentrate on Chinese, and then another half to concentrate on English.
I tried language diaries, but I don't find physical ones very useful because I recieve no input. I actually really like the format here on iTalki, because you can submit your Notebooks and most of the time people are kind enough to correct them! I've also always found the idea of using videos as speaking practice very useful, like posting videos speaking your target language, but I wish there was some specific language-learning video-posting platform. YouTube is too scary HAHA