The single purpose range extenders were useful back in the third generation of zwave when not every device ran at full power. But now that we are at the fifth generation (Z wave plus) , these devices don’t do anymore than any other mains powered Z wave device does. So instead, you might as well just get a zwave plus light switch or pocket socket or plug-in sensor and get double use out of the device, you will get the same “extend the mesh” result.
That said, your other devices won’t know they are supposed to use any new repeater unless you run a Z wave repair utility after you install the new repeater. They’ll just continue to use their old neighbor tables.
So when is the last time you ran the zwave repair utility? And what were the results? Also, the utility should complete fairly quickly, but it takes time for each individual device to update its own neighbor tables, so you may not see improvements until the next day. So be patient when evaluating the impact of new repeaters.
You might find the following FAQ helpful. Read post 11 first, then go back and read the whole thread. (this will also give you more information about the Z wave repair utility.)
As far as reaching your other buildings, you might also find the following how to in the community – created wiki helpful:
http://thingsthataresmart.wiki/index.php?title=How_to_Automate_an_Outbuilding