I have found that inline math for lcdout cmd on a pic16 turns to crap, serout2 may have the same issues

you probably need to do the math first then print result

i would do it this way

hh=hh+3 ;utc+3
hh=hh//24 ;REALLY SHOULD ADD A DAY TO DATE TOO IF day changes
serout2 lcd,32,[$73,$00,$04,$00,$FF,$E0," TIME: ",dec2 hh," :",dec2 mm," :",dec2 ss,$00]
pause 100