The normal trinket is 553 lvl, and it gets scaled down to 522.
Since 1 item level equals approximately 0.935% increase in stats,
39/1.00935^(553-522) = 29.2259878171
It will probably be around 29% increased recovery rate for 522 downscaling.
The cooldown recovery acts little differently from direct cooldown reduction.
for example lets assume that skill is 100sec cooldown.
The direct decrease by 30% would be 100*0.7=70 sec cooldown.
but increased recovery rate would mean 100/1.3=76.9230sec.
Therefore, if its 39%(553 level) it should be 28.06% reduction.
if its 29% it should be 22.49% reduction.