Meta-analysis - Can I investigate mediation effects for the effectiveness of training

Hello everyone,

I am currently working on my Master thesis on moderators and mediators for the effectiveness of cross-cultural training (CCT). I am actually writing a literature review, but want to end my thesis by judging to what extent the included studies could also be compared statistically via a meta-analysis. I understand how moderating effects can be examined. But I am not sure whether I can prove a mediation effect across various studies.

Many of the researchers in the field believe that CCT can only improve the performance of trainees if it enhances their adjustment in the first place. I therefore hypothesize adjustment as mediator for the CCT-performance relation. This was already investigated by two of the 23 studies in my sample.
My question is: Is it possible to prove the mediation effect of adjustment for all the studies that measure the impact of CCT on adjustment and performance as well as the correlation between adjustment and performance. And if yes, how can I do this?

Thank you so much for your help!