You can not put speed for the zombies from subplugin you need to edit the source code because it checking the zombie speed every respawn
Open source code and find the code that giving the zombie speed when using "bb_register_zombie" native and create a new native for that if you want using it on subplugins for example :
PHP Code:
new bool:iUseSpeed[ 33 ]
set_user_maxspeed( id, iUseSpeed[ id ] ? Custom Speed : Array Code )
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