I might be wrong, but I think autobonus only triggers when attacking or being attacked:
From docs/script_commands.txt:
*autobonus <bonus script>,<rate>,<duration>{,<flag>,{<other script>}};*autobonus2 <bonus script>,<rate>,<duration>{,<flag>,{<other script>}};*autobonus3 <bonus script>,<rate>,<duration>,<skill id>,{<other script>};*autobonus3 <bonus script>,<rate>,<duration>,"<skill name>",{<other script>};What these commands do is 'attach' a script to the player which will getexecuted on attack (or when attacked in the case of autobonus2).
If you want to have it being triggered when attacking, maybe you are not getting it triggered because the chance is very small (0,10% I think)?
And your bonus heals 1 point of HP, maybe you are not noticing it
From docs/item_bonus.txt
bonus2 bHPRegenRate,n,x; Gain n HP every x milliseconds
If you want to try a higher chance, I edited your script to test here: (It heals 1000 of HP, though I'm not sure about the rate, but is more frequent)
autobonus "{ bonus2 bHPRegenRate,1000,10000; }",5000,10000,BF_MAGIC,"{ specialeffect2 EF_HEAL; }";
Sorry, but I can't help more than this because I've never used these commands