(resending, as I accidentally only answered to joseph)
You must build against Pd-0.54 (as there's obviously no compile time check for the actual Pd version).
Pd-0.54 has been released after Debian/bookworm, so you cannot use the Pd bundled with your Raspbian/bookworm. Either compile Pd yourself, or use the one from Debian/backports: https://backports.debian.org When compiling of yourself, you must make sure that the build system can find the headers.
Personally I think this is a bug in ELSE, and would file a bug that it ought to be buildable against older versions of Pd (even if that means that some functionality is missing).
https://github.com/porres/pd-else
mfg.sfg.jfd IOhannes