In the errata for Tome of Beasts 3, on Page 222, it changes the Challenge of the Grolar Bear to 8. This should change the Proficiency Bonus to +3 and modify the to-hit and DC in the actions, but this is not included in the errata.
#Grolar Bear CR change didn't change PB
half coyote
dreamy pebble
The errata corrects the XP note from 700 to 3,900, but the CR doesn't actually change. The to-hit and DC calculations in the stat block should be accurate.
The Bite and Claws are showing as +10 to hit with a STR of +7 and PB of +3, and the Multiattack's save DC is CON-based with 8 + 4 (CON) + 3 (PB) for a total of 15. That's what I see in my PDF. It's very possible I have a more updated PDF than the original printing, so if you see something different in your copy, let us know!
half coyote
Oh! I missed the word "Alpha"!