There are two possible reasons for the increase in uncorrected errors for 10:
1. Local electrical noise interference on VHF-hi, which has higher noise levels than UHF. If the noise is constant, then you should also see a reduced SNR. I have a fairly strong CH 10 signal, but its SNR is only 16 because I also have a high noise level on VHF-hi.
2. Multipath interference for the CH 10 signal. This could be from static reflections, or it could be dynamic multipath from moving objects, like vehicles or aircraft, or when signals have to filter thru trees that are moving in the wind. A possible solution would be to use a more directional VHF-hi antenna to replace the V in the C2V. I think the C2V has an integrated UVSJ, so you might need an external UVSJ to combine the new VHF-hi antenna with the C2V.
IF the problem is multipath, and IF a more directional VHF-hi antenna helps, then another alternative would be to replace the C2V with a UHF/VHF-hi combo antenna.
Check out this theory with ADTech before doing anything drastic.
IIRC, the early TiVo tuners didn't handle multipath reflections very well.
https://www.google.com/?gws_rd=ssl#q=TiVo+tuner+doesn't+handle+multipath+very+well
You could test this theory in a low-cost way by connecting your antenna system (or just the C2V) directly to a TV and see if there was any difference.
OTA signals are constantly changing. If you want a real-time side-by-side comparison between two tuners, you can insert a splitter after the antenna system to feed the Roamio tuner and a TV, and feed a second TV connected directly to the splitter.
If something bad happens as shown on the TV connected to the Roamio tuner, you can see if it also happens to the TV connected directly to the splitter.
I forgot; where are your antennas located, inside or outside?