Well spotted, I noted and posted about the Droid Sentries a while ago...
https://forums.galciv2.com/?ForumID=274&AID=114991&cmd=myposts#885009
I posted a follow up post as well about them when the 1.2 patch was in beta...
https://forums.galciv2.com/?ForumID=274&AID=119270&cmd=myposts
Either I'm unlucky or it is not important enough for a fix. What I suggest is that you edit this file... (mine is found in D:\TotalGaming\GalCiv2\Data\English)
GC2Types.xml (making a backup of the original first)
and then edit the values that you wish to change. Check it out afterwards in the Galactopedia to see if those values have been entered correctly, if you wish.
The Droid Sentries entries look like (this is for level 2)....
DroidSentries2
PD
4
2
100
6
Droid Sentries II
Missile defense.
pointDefense0
pointdefense
Point Defense
Droid Sentries II
Defense.x
The forum isn't displaying the above Droid Sentry entry in its correct form - ah well.
I can't remember now but there are some other defence / weapon values that don't seem to be correct but they too can be adjusted in that file.
Good luck