Author Lother Arsana has this to say in "Authenthic Recipes from Indonesia," (Periplus Editions):
"Candlenuts (buah kemiri) are waxy, cream-colored nuts similar in size and texture to macadamia nuts, which can be used as a substitute, although less-expensive raw almonds or cashews will also do. Candlenuts are never eaten raw or on their own, but are chopped, ground and cooked with seasonings and added to curries and spice mixes for flavor and texture. They go rancid quickly because of their high oil content, so buy in small quantities and keep refrigerated."
The NY Times published a Laksa recipe from the renown Violet Oon, which called for "candlenuts or macadamia nuts." One recipe by no means can set a standard for an entire cuisine. It does, however, indicate that if someone with the credentials of Violet Oon was willing to use macadamia nuts in place of candlenuts in laksa, then macadamia must be a fair good substitute -- even if the substitution was made simply for American cooks. Interesting article touching on laksa origins and the recipe here:
This blogger's post re "The Food of Indonesia" discusses equivalencies found in that book (raw macadamia nuts for candlenuts), and also the matter of not knowing for sure how close the substitution really is to original ingredient. This book, by the way, may be another version / print (as in, mostly dupe) of the book I cited above.
In response to your request for recommendations, I recommend you simply enjoy those substitutions which taste good to you and don't get too hung up on how the dish "should" taste. Even if you use candlenuts, all the ingredients available to you may differ some from those in recipe's origin, no matter how closely you try to follow the directions. That's inherent nature of cooking. For every recipe you try, there will countless more variations on it, even in region it was produced. I've found in my reading that even culinary professionals, who may argue authenticity of ingredients or dishes, will roundly agree that what matters most is how good your dish tastes. From the beginning of time, cooks everywhere have had to make substitutions based on what is available. It's actually one of the joys of cooking -- so åmake the best doggone version you can and enjoy it! That's my recommendation!