Yes the mode +L #chan requires channel owner privileges (Basically it defines L
inked channel to which to send users when channel limit +l was reached).
Mode +f should be easier to test since this is limited to all channel ops.
ie: /mode #test +f 10j:30
Unreal has a quite good section describing the antiflood feature in detail as well: https://www.unrealircd.org/files/docs/unreal32docs.html#feature_antiflood
mIRC itsself can deal with the mode just fine. It shows up when you join the channel, when someone sets it or unsets it.
It just seems that $chan(#).mode is unable to return the parameters for other modes than +k and +l
In addition I also noticed that the parameters for +f and +L wont show up in the titlebar either (while limit and key show up just fine)
So channel window titlebar reads: #test (Network, Nick)  [+fLnrtlk 100 key]
Debug output for /mode #test +ntlkLf 100 key #test2 [1c,2j,3k,4m,5n,6t]:30
<- :Brax!Barco@Brax.-address- MODE #test +ntlkLf 100 key #test2 [1c,2j,3k,4m,5n,6t]:30
-> irc.-address- MODE #test
<- :irc.-address- 324 Brax #test +ntrlkLf 100 key #test2 [1c,2j,3k,4m,5n,6t]:30
<- :irc.-address- 329 Brax #test 1437987097
mIRC also parses it fine and shows on channel:
#test +ntrlkLf 100 key #test2 [1c,2j,3k,4m,5n,6t]:30
#test created on Mon Jul 27 11:51:37 2015
Also I noticed few topics here on same/similar issues but they all seemed to be sort of open ended.http://forums.mirc.com/ubbthreads.php/topics/241940http://forums.mirc.com/ubbthreads.php/topics/230583
And maybe even this: http://forums.mirc.com/ubbthreads.php/topics/242701