Use a validators' consensus public key to find the signing-info for that validator:
 
$ <appd> query slashing signing-info '{"@type":"/cosmos.crypto.ed25519.PubKey","key":"OauFcTKbN5Lx3fJL689cikXBqe+hcp6Y+x0rYUdR9Jk="}'
 
Usage:
  seid query slashing signing-info [validator-conspub] [flags]
 
Flags:
      --height int      Use a specific height to query state at (this can error if the node is pruning state)
  -h, --help            help for signing-info
      --node string     <host>:<port> to Tendermint RPC interface for this chain (default "tcp://localhost:26657")
  -o, --output string   Output format (text|json) (default "text")
 
Global Flags:
      --chain-id string     The network chain ID
      --home string         directory for config and data (default "~/.sei")
      --log_format string   The logging format (json|plain)
      --log_level string    The logging level (trace|debug|info|warn|error|fatal|panic)
      --trace               print out full stack trace on errors