Question is: do these codes remain the same throughout all future bmax updates?
No. That's why they use constants. If yes, there's no problem using the codes :P
The question you want to be asking is not "Is there a problem with hardcoding values into my application" (although the answer for this is yes). The question you should be asking yourself is "Why would I want to".Remember in the old days when you used to hardcode absolute addresses in your assembly code, instead of using labels and relative addresses like sensible people? Remember how much distress that caused all your friends with different RAM configuration than you? Same deal, different day.