I have a modified XE1 (720nm) my experience of hotspots /lens suitability is as follows:
14 F2.8 - excellent all apertures
16 F1.4 - ok no hotspot but not as good as 14. Normal colour performance exceptional.
16-55 F2.8 - mild hotspot.
23 F1.4 - Excellent all apertures
35 F1.4 - Excellent, but only used up to F11
That's my experience, I hear that 18-135 is good, as is 50-140.
Hope this helps