I am surprised that you could not control the font size of the comparative texts in the Biblical terms tool by adjusting the language properties of the resources in question. I just tried it again and it works. I did have to restart the Biblical terms tool. If I adjusted the language settings of the NIV in Portuguese for example, while the Biblical terms tool was already open (and NVI-P was a comparative text), nothing happened. But if I closed and reopened the Biblical terms tool then the tool used the new language settings for Portuguese.
Bible_terms_tool_font_size.png1055×620 168 KB
In this screenshot the NVI-P. RET4 and BPT09 all are using the Portuguese language settings which I have set at 18 point.