Hi

yeah as Goat says headstanders would be okay with kribs as said either Annostomus Ternetezi or the Marbled Headstanders would work in this tank Spoted Heastanders might work depends on the temperment of the kribs though.
I looked them up and would prefer to have some top/middle fish, because of having the loaches & getting the 2 Kribensis.
Bloodfin Tetras might work as they are known to stay in the upper levels of the water and will stay out of the kribs way naturally, they are also quite a shy tetra that needs to be in big groups I think a big group of 20-25 of these would work very well with the kribs and due to the tetras tight shoaling nature the kribs might be put off doing any damage to them.
I was thinking of 12, so probably not what I am looking for.
Personally though I would probably go for a school of barbs if you want a splash of red in the tank you cant beat barbs, dension barbs
My 1st choice, but can't afford them, black ruby barbs and odessa barbs could be more robust alternatives for your tank. The black ruby barb would be my favorite as they are found the closest in the wild to kribs as they are widley distributed all over asia and parts of africa.
Wills