Now I understand your issue but it has been resolved seemingly, as the L. number alone seems not to be sufficient for recognizing a composition so it cannot be mixed up with another. Reason being that two different versions of the Lesure catalogue are around, the original and the 2001 revised version.
The exact assignments by roon seem to be made solely according to the so-called ´CD´ number which is clearly defined (and identical to the L(2) number? Not sure about that):
CD 111 - La mer
CD 105 - Images
CD 109 - L´isle joyeuse
It is true several musicologists have been compiling Opus directories for each and every one of these composers. But in all these cases there seem to be either a primary one (like WAB for Bruckner, Köchel for Mozart or Deutsch for Schubert) which roon is following or several different systems have a clear definition of how one Opus number translates to the other (like BWV and BC for J.S.Bach).
Franz Liszt is an interesting case as the situation with his oeuvre is misleading:
Even the Searse number (S) is not comprehensive and I do have a bunch of Liszt compositions which are not recognized at all as they do not exist neither in TiVo/Allmusic nor any of its opus directories so they stay just as they are:
It is not really clear if they qualify as compositions on their own or are just works of others (re-) arranged by Liszt.
I do not doubt there are mismatches but in most cases they just create new, unrecognized compositions. Usually by tagging according to TiVo’s syntax and doing a bit of merging compositions it can be resolved.