One Less Talent For On Legndary Setting in Mass Effect 1?

As far as I can tell, both modes give the same total number of points at max level for a new character (100 for the player and 80 for the squad mates).

It was broken in the original release, so that might be causing some weirdness if you're using an existing save.

I did a test run for the heck of it. I don't have the image from one of the chracter creations, but I finished that one using classic mode starting at lvl 57 (lvl 29 on legendary). After getting to 60, I earned 3 talent point for each of the final three levels. On another creation that I used as an imprt to ME2, it was also on  lvl 29/57. There I ran the game out on legendary and got 2 points, one less than running at classic from lvls 58-60. As you can see, when I hit lvl 30, I got just 2 points.

Is this a new or existing (pre-patch) save? And was it already Level 29 before the patch?

No, even then, a pre-patch save wouldn't make the patch not work. Before the patch, I couldn't advance to 30 on legendary,. 

The only issue I can confirm is that if you are Level 59 on classic mode and switch to legendary (will show up as Level 29), you still can't level up to 30 (you have to switch back to classic for the final level).

Every combination I looked at always gives the same number of talent points when reaching max level, but I only have access to characters created after the patch. It's possible that the fix is not retroactive in all cases or there's something specific with your playthrough or with the game on Xbox.

You miseed what I am saying. The patch fixed the level sticking issue no matter if the save eres before or after the patch. IOWs, if you are on lvl 29 and make to to 30, you'll make it to 60 as well on classic mode, and vice-versa going from 59 to 60 will give you lvl 30 on legendary. Hitting the level numbers hs been fixed.

You hit lvl 29 on legendary, then the player is at lvl 57 on classic. Playing either way going from 28 to 29 on lengendary will lvl you from 56 to 57 on classic, and vice versa again

The issue is hte point allocation at the last few lvls of legendary only give 2 ponts per lvl (lvl 28 thru 30 AFAICT), where as anything after lvl 35 on classic in one point. So, once at 57, getting to 60 will earn 3 more points for the last three lvl-ups where on legendary lvl 29 to 30 gives just two.

No, I understood that, but what I'm saying is that I can't replicate that issue with a new character that has been created post-patch. (Playing on PC, so it's simple to just use the console to add XP.)

If the character is Level 29/57, they always get 3 points upon the final level up in legendary mode. If they're 29/58, they get 2 points. If they're 29/59, however, then they will not level up to max level (even after the patch) without switching back to classic mode. (I have no idea why they even allowed switching for an in-progress game given the weird way they implemented this feature.)

Without knowing what the original problem with leveling was (or how they fixed it), I can't say if it's something that might be caused because your save game was already "max" level before the patch (since the original stopped you at 29/57 and bugged out). I haven't been successful in replicating any other issue with leveling on either mode.