I do not have any personal feedback to give you on Lemania, though I have never heard anything negative to my knowledge.
Is this school for your daughter whom you are seeking help for on your other thread, and does she only speak English?
If you are still open to other school recommendations then please have a look at eĢcole Le Valentin in Lausanne http://www.levalentin.ch/ . Le Valentin is a private school too, and does have children from other nationalities but everything is in French.
I mention Le Valentin to you because of your other thread, perhaps this may interest you. We placed our children there following some tough times in 2 separate state schools. At the time 1 of our children was required to go to a psychiatrist following some serious bullying that we only discovered after it had been going on for a while. Our other, child who suffers from dyslexia, was being let down by their particular state school who never followed through the recommendations given by the doctor to facilitate their learning, and as such they fell ever more behind with frustration, poor self-worth seeping into their everyday life. Once at Le Valentin, both our children grew enormously in self confidence and have flourished in their own individual ways. Apart from the teaching side which was far better than with the other 2 schools, the care, concern and support offered to them (and us) for each of their "problems" was outstanding. Our dyslexic child is now top of their class, the other graduated with great results and is now at college in Lausanne.
Good luck.