Yes, electronic seals are legally valid in Indonesia. Electronic seals have been regulated in Pasal14 of UU 10/2020 Concerning Stamp Duty and Pasal 5 Paragraph (1) of UU No. 11 of 2008 (UU ITE) which stated that electronic documents are valid and legal evidence.
Electronic documents that use eMeterai have the same legal force as paper documents with physical seals. However, make sure to buy eMeterai from a legitimate distributor such as Mekari Sign.