We've tried hard to support most pluto configurations in charon. But please keep in mind that IKEv1 in charon is a completely new implementation and that it might behave differently than IKEv1 in pluto.
The ipsec.confconfig setup section ceased to support any of the pluto specific keywords as well as plutostart and charonstart. NAT-Traversal is always enabled in charon, for both IKEv1 and IKEv2. The IKEv2 eap keyword has been removed.
The authby and xauth keywords are still supported, but deprecated. Please migrate your installation to the leftauth / rightauth keywords. XAuth is configured as multiple rounds using leftauth2 / rightauth2 keywords (i.e. leftauth=pubkey, leftauth2=xauth). To configure the new Hybrid Mode, define leftauth=xauth and rightauth=pubkey.
The pfs option has been removed and the default for IKEv1 has been changed from enabled to disabled. To enable PFS both IKEv1 and IKEv2 now use the same syntax, namely listing a Diffie-Hellman group in the ESP proposal, esp=aes128-sha1-modp2048.
The IKEv1 responder narrowing keyword rightsubnetwithin is not supported anymore, but is an alias for rightsubnet. The leftsubnet / rightsubnet definitions are automatically narrowed if required. Please be aware that IKEv1 does actually not support narrowing, and returning a smaller subnet than requested might confuse the initiator (but works fine with charon). To interoperate with other implementations, make sure your subnet definitions match exactly.