values for lambda and theta

[MatsuSui]

I have tried harmony for batch effect correction for my single-cell RNA-seq data to intergrate tumor and normal tissues, but when I used default parameter values, I found one problem is that some tumor cells mixed with normal cells in the same cluster.I know I can adjust parameter values such as decreasing theta and increasing lambda to seperate tumor cells from normal cells. I have a question that if there is a recommended value range for lambda and theta? Can I choose theta=0.3 ?