I don't think it would be broken. 17% from convi and 8% (rounded down from 8.2%) is still 25%. If monster has 125 LR it would put him on 100% to resist, and 100% resistant monsters (or higher then 100%) are still considered immune to element.
And no, LR will not work at 100% after immunity is broken by conviction. It will work on 8% rather than 41% (standard 20% penalty for LR when dealing with immunities). All other sources of minus enemy resist other then LR and Convi will work 100% on broken immunity however.