Renaissance pieces are usually indexed based on their starting lyrics and that should be the case here. The score page for Deploration should be merged into Nymphes, so Nymphes is the one that survives and there is only one score page linking to all editions of the same musical work. A redirect from Deploration to Nymphes would be good, though.
Good reasons to follow the convention of titling based on lyrics:
1. It avoids discrepancies in the wording or even the language of the description. The description is more likely to vary based on the particular edition. For example, this piece is also listed elsewhere under Déploration de Jehan Ockeghem.
2. Deploration is hardly ever used without Nymphes, but Nymphes is often used without the specific term Deploration. See e.g. this recording of Renaissance laments.
3. Titling based on Nymphes rather than Deploration is consistent with other CPDL practice as well, e.g.
4. It's easier for non-native French speakers to remember Nymphes de Bois because they sing it; harder to remember La Déploration...
The main thing is to put pieces where people expect to find them, even if it means more work the few times a score page uploader happened to choose otherwise. In this case, they should go under Nymphes.
I have just moved the score information from this page to Nymphes des bois (Josquin Des Prez) and will leave a redirect on this page to the combined page. I agree with Vaarky's reasons above about titling, although (oddly enough) I have often heard the present work called simply the "Josquin Déploration".