I think the font size of the legends in Visual objects is too small. I haven't found a possibility yet to change it and NI support also says it's not possible. Does somebody know a workaround? (I'm not talking about the font size of the measured values, of course, that'd be easy!)
Unfortunately I just can confirm what the support told you before. There is no workaround except you add a graphic (WMF file) to your DAC scheme. But I will add your suggestion to the list of further DIAdem functions maybe that have it in one of the next DIAdem versions.