Roon only “explicitly” uses your local title tags in all scenarios with single part works. Even so, there are relatively frequent posts where roon has not applied that general rule consistently.
With multi-part works roon does not in general respect your naming convention unless you “unidentify” the album. Instead it seeks to match your homegrown naming convention to the canonical form supplied by Rovi/allmusic. That is why Op. 19 and Op. 58 in your screenshot looks nothing like your homegrown convention for Op37.
This problem of failed grouping for multi-part works is extremely common in roon so if you have not seen it before then you have been very fortunate. In fact roon introduced parsing for WORK/PART tags years ago precisely to provide a manual override when its auto-grouping fails.
The surest way of solving your problem is just to edit the WORK/PART tags of the rogue composition to comply with the Rovi/allmusic canonical form as has already been suggested. You don’t seem to want to do that so you can also try unidentifying the album to see if you get the result you want. Sometimes a more minor edit will also work. For example changing Op37 to Op.37 or changing your delimiter from “-” to “:” so that your homegrown convention complies a little more closely to the canonical form and roon can make a match. But there are no guarantees so mostly editing the WORK/PART tags is the quickest solution.