I might be mistaken, but isn’t the reduction in 99,99% only applicable to Andalucía, not Lanzarote ? Art. 9 of Law 3/2004, of 28th December modifies article 20.2.c of Law 29/87 for Andalucía only I believe.
In Lanzarote, If you dwell in the house within those 10 years its 95% but you must have lived the 2 immediate years with that person who dies (general regime). I’m sure Lanzarote (Canary Islands) has its own laws and specific allowances which I just don’t know.
Although each community has their own laws and specific allowances as well as those granted by the Spanish State which is the general regime common to all regional communities.