no, there's no reason it's require. It should use the xml file to get parental level from it, EXCEPT for real NAND installed channels which are loaded before the xml file so the parental level is loaded with a default value. you'll need to add that level manually.
or maybe re-downloading the xml force all games to be set back to proper values, but it should affect only real NAND channels, not wii games, gamecubes games or emuNAND.
it's a known bug present for a long time, I tried to fix it once but couldn't until now. I'll have to spend times on it (which I don't have) to fix nand channel's parental level.
you said you have that bug with games added to your hdd, so I suppose it's wii games and not channels. you shouldn't have that bug, so it's another bug I'll have to check.
how do you add the game ? from computer, or by inserting a disc in the console and choosing install? just to know if the issue is only with a specific install method, or both.
I add the game from the computer side in general to the USB hard drive (it's 250GB 2.5" hard drive with FAT32 with 32k cluster size). basically here is how I have things setup on my USB 2.5" hard drive... "wbfs\Game Name [XXXXXX]\XXXXXX.wbfs" (where XXXXXX is the numbers/letters tied to the specific game)
also, my system is pretty basic (basic Letterbomb hack etc and then d2x stuff like my signature says is the gist of it) and both of my Wii's act the exact same way as I moded the systems about a month ago and have only been using USBLoaderGX r1268 on it (as far as that program specifically goes) and I have it so the Wii system boots directly into USBLoaderGX when I power it on and have the USBLoaderGX channel installed so it shows on the official Wii menu, if this matters at all. I am using the REAL NAND as I don't have any emulated NAND stuff setup (maybe it's something ill play with in the future if there are any benefits(?) as I have a 8GB Sandisk SDHC card in the SD card slot).
but anyways, ill try to be a bit more specific on how I triggered this issue...
just testing this stuff out a a moment ago... when I added only one game (which was Mature rated if this matters(?)) and updated cover art etc the parental lock functioned as expected as the bug did not trigger. but when I added seven additional games and updated the cover art and then adjusted parental control back to only show the 'Child 7+' stuff (which allows games 'Everyone 10+' and younger) there are still a couple of TEEN rated games showing, which should not be happening.
plus, to go even a bit further... I noticed when I lower the parental lock to the 'controllevel = 0 (Everyone)', which should make it filter anything out in the 'Everyone 10+' or higher rated, it's also listing some of those seven new games I added that were rated 10+ along with the two TEEN rated games which should not be listed given the parental control setting should only allow the basic EVERYONE (not the everyone 10+ or teen etc).
so basically... two '10+ rated games' and two 'TEEN rated games' are listed when they should not be but for some reason it does filter out one of the three teen games I added when I turned on the LOCK. but at this point, in order to fix things, when I update the .xml file it will fix this problem and the parental lock functions as expected and filters ALL games once again properly. I have seen this issue happen on both of my Wii consoles as I have added games to them over the last month or so.
these where all added on the PC side of things with the basic method I described above with the whole XXXXXX stuff.
also, the USBLoaderGX r1268 settings are all pretty much default except some minor stuff like having it exit back to USBLoaderGX from inside a Wii game by selecting 'Wii Menu' and I recently changed to IOS 250 from it's default of 249 but I doubt this matters as I had the issue before adjusting that type of stuff.
and yes, it's to do with Wii games themselves (possibly some Gamecube games to but I did not test the issue on those at this time). I have some Gamecube games on there to (which should be running through newest Nintendont) but the test I just did above all I did was add some new Wii games that were previously not on the hard drive so they are completely new to the USBLoaderGX r1268 program.
p.s. I 'might' be able to do a little testing with the 'inserting disc and choosing install' stuff but the info above basically applies to the adding game from computer method.
EDIT: after all of the above happened, I did not update the .xml file, and then put a couple of more games on it, one Gamecube game and a additional Wii game, and updated the covers by pressing 1 like usual, both have the 'Everyone' rating and noticed when LOCKING USBLoaderGX, which was set to 'controllevel = 0 (Everyone)', which means those two games should be listed, that it does not even show those two games I added when USBLoaderGX r1268 is locked. but when unlocked ALL games show up like normal as expected. but the only way I have found to fix that stuff is to update the .xml file again at which point things will work perfect as long as I don't add additional games etc in the future as I can shuffle around parental lock settings without any issues as long as I don't add some more games. so as you can see things are out of whack. maybe that bug is triggered by adding more than one game at a time?