As far as I understood it, monks get proficiency with all weapons listed as monk weapons. At least that is how I run it.
Where does this come from? The core rules are very clear:
"Weapon and Armor Proficiency: Monks are proficient with the club, crossbow (light or heavy), dagger, handaxe, javelin, kama, nunchaku, quarterstaff, sai, shortspear, short sword, shuriken, siangham, sling, and spear."
Where does it say in the rules that are automatically proficient with weapons marked as "monk"?
If you cannot provide that, you are playing under a house-rule that monks are automatically proficient with monk weapons not listed in the class description.
Yes, I agree it's a reasonable and logical rule if for no other reason than it accounts for subsequently published material. No, that alone doesn't make it official.
You have wayyyy too many house rules. You must have a specific group you play with as I doubt most common players enjoy that many house rules.
That's sort of an odd statement to make, unless
THE STREAM OF THE SKY has detailed a list of house rules that he employs, since so far I see only one person stating a house rule they use. (Well, two because I do the same thing)
In any event, Paizo has an organized play program called the Pathfinder Society. It's sort of a big deal.
From the Guide to Pathfinder Society Organized Play, "As a Pathfinder Society Game Master, you have the right and responsibility to make such calls as you feel are necessary at your table to ensure that everyone has a fair and fun experience.
This does not mean you can contradict rules or restrictions outlined in this document, a published Pathfinder Roleplaying Game source, errata document, or official FAQ on paizo.com, but only you can judge what is right at your table for cases not covered in these sources."
Note that your ruling of allowing monks to be automatically proficient in all monk weapons (and mine as well) is invalid for Society play, unless there is something in a published game source, errata document, or official FAQ granting it.
As it is, look in the APG - the monk weapons in there are explicitly stated to also be monk proficiencies. However, the ones in UC are not.
Either a weapon has to be explicitly stated to be proficient by a monk, in which case the APG handled it correctly and the UC weapons do not grant proficiency, or monk weapons are automatically monk-proficient, in which case the APG is wrong by stating a rule as if it were covering an exception.
My take on it is that it's another example of how shoddy UC is, but for all I know it was a design decision not to make them automatically proficient weapons. My crystal ball is broken, so I can't read the designer's intent, so I'll either stick with the rules as written or explicitly make a house ruling.