Yes, the code will drop all syslogs with facility SEC and mnemonic IPACCESSLOGP.  However, the logic will be the same.  You may need to match on other parameters, though.  If you want to look for something in the body of your message, use $::orig_msg.  For example:

if { [regexp {10.1.1.255} $::orig_msg] } {
    return ""
}

This would get wrapped in that previous check for facility and mnemonic.

To escalate the severity of a message, you can use this filter script:

if { [info exists ::cli_args] } {
    set args [split $::cli_args]
    if { [ string compare -nocase [lindex $args 0] $::mnemonic ] == 0 } {
        set ::severity [lindex $args 1]
        set sev_index [ string first [lindex $args 0] $::orig_msg ]
        if {  $sev_index >= 2 } {
            incr sev_index -2
            return [string replace $::orig_msg $sev_index $sev_index \
                [lindex $args 1]]
        }
    }
}
return $::orig_msg

You need to register it with two CLI arguments:

logging filter flash:escalate.tcl args IPACCESSLOGP 5