Humble Bundle splasher region restricted ?

yes

Splasher ✘ is region locked for RU/CIS: SteamDB ✘. It might also be region locked for China (SteeamDB ✘ - needs confirmation).
There is a warning that Splasher ✘ can't be activated in New Zealand, but there is no such region lock on SteamDB, therefore the key is probably redeemable.

I can't redeem it in Italy. My friend did it tho.

I cant redeem it in Brazil and my friends in Indian and Russian store cant redeem it either...

when I tried to make it giftlink I got this info:

This key is not available in the countries listed below. If the person you're gifting this to lives in one of them, Steam might prevent the key from being redeemed.
AM
AZ
BY
CN
GE
KG
KZ
MD
RU
TJ
TM
UA

I'm from EU