Consensus in bitcoin network is not about validation of transactions.
that is exactly what consensus is all about! consensus or consensus rules are the set of rules that are enforced by any bitcoin full node client and it includes validation of blocks and their transactions.
https://en.bitcoin.it/wiki/ConsensusNope, that article in the wiki you refer to is misleading in some way as network consensus (defined by Satoshi and referenced in my above post) differs from consensus rules as to the transaction validation. Those rules to validate transaction are the the set of rules to ensure that transactions in the block follow correct protocol to build them (all scripts are valid and so on) and the record of those transaction included into the block is correct.
For clarity, these rules should be called hard rules or the rules of Bitcoin instead of consensus rules.