If you look at google maps, there are 7 properties that are "neighbors" to Garrido. There is a large plot of land to the north roughly the same dimensions as his property, which I'm guessing is the rental place that was included in the LE search. To the south the original plot appears to have been subdivided into 4 units, 3 of which adjoin the Garrido property. The eastern most one only adjoins the front section of the property and is not likely to have been able to see what was going on in the back yard. There are also two smaller subdivisions to the south with adjoin the back yard, and those folks are likely the only ones who would have noticed any wild parties.
On the west are 3 larger properties. The southern most one has a house on the western edge and some sort of light industrial operation going on in the back yard (sheds and trucks, paved surface). The northern most one has a house on the western edge and is fully paved in the back with a number of heavy trucks parked there. Again, some sort of light industrial operation. Both of these properties adjoin the Garrido property at the corners only, and are unlikely to be the source of "party" stories. The center property on the west has a house at the western edge, together with a swimming pool and groomed garden, but beyond that is an unkept wild area that is empty except for bushes. An abandoned car can be seen in it. Whoever lives at that property is unlikely to know what was happening at the Garido's, since it is clear that they don't spend much time, if any, in the back part of the yard.
That really leaves just two residential properties to the south that could have "witnessed" these parties. Rogers must live in one of those.
It would also be useful to know when exactly these parties took place. Was it recently, or many years ago? That would impact on the reliability of the witnesses.