In Nethack3.4.3, can an altar be wished for?

Chasing through the source code, the function readobjnam() in objnam.c is responsible for translating object name into internal game structures, and determining what you can (and can't) wish for. Altars are in the "wizard-only" section of the function, along with traps, fountains, and other dungeon features:

    if (wizard && from_user) {
       ...
            if(!BSTRCMP(bp, p-5, "altar")) {
                aligntyp al;

                levl[u.ux][u.uy].typ = ALTAR;
                if(!strncmpi(bp, "chaotic ", 8))
                    al = A_CHAOTIC;
                else if(!strncmpi(bp, "neutral ", 8))
                    al = A_NEUTRAL;
                else if(!strncmpi(bp, "lawful ", 7))
                    al = A_LAWFUL;
                else if(!strncmpi(bp, "unaligned ", 10))
                    al = A_NONE;
                else /* -1 - A_CHAOTIC, 0 - A_NEUTRAL, 1 - A_LAWFUL */
                    al = (!rn2(6)) ? A_NONE : rn2((int)A_LAWFUL+2) - 1;
                levl[u.ux][u.uy].altarmask = Align2amask( al );
                pline("%s altar.", An(align_str(al)));
                newsym(u.ux, u.uy);
                return(&zeroobj);
            }

You can only wish for items, and an altar isn't an item. Wishing for an altar won't work.

You seem to have two issues:

As others have mentioned, the answer to your direct question is that altars can't be wished for outside of wizard/debug mode.

If your level isn't high enough for the quest yet, I encourage you to continue exploring downward. There's a good chance you can still find an Altar Room or Temple before hitting the pre-castle mazes. Otherwise, let's be honest, the walk from the quest portal to the mine-town really isn't all that far in the grand scheme of the game.

Unrestricting Magicbane or Stormbringer:

There are two ways of unrestricting a class of weapon.

• Gifts in response to Sacrifice at a co-aligned altar:

  You're an Elf, therefore Chaotic. The good(?) news is that you are eligible to receive both Grimtooth and Sting as a technique to unrestrict Daggers, and thus Magicbane.

  Stormbringer on the other hand is the only runesword in the game; as it already exists in your game, you can't be granted another.

  From the information you've provided, your gift opportunities seem to be:

  • 3 chances at a longsword. Hope for Frostbrand, one of the two highest damage weapons in the game. If you get one of the others, Wish for Frostbrand. It's the only Artifact on this list you really want anyway.
  • 2 chances at a dagger. They both stink, but at least they unrestrict Magicbane
  • Orcrist, an Elven Broadsword, but hey, it's a 1/9 chance to unrestrict Stormbringer.
  • The war hammer Ogresmasher, a crap weapon that you can become Expert in.
  • The Morning Star Trollsbane, an only slightly better weapon that you can become Expert in.
  • The Silver Saber, Werebane. You've already got decent silver damage covered as you're already able to make Skilled with the Silver Spear, but at least this unrestricts saber if you want to wish for Greyswandir, the game's other big damage weapon.

  As a game's artifact count makes wishes for other artifacts (such as other class' Quest Artifacts) less likely to succeed, and the difference between Unskilled and Basic skill levels becomes trivial at higher experience/luck levels; I'd probably not spend too much time sacrificing for junk artifacts.

• Crowning:

  You already own Stormbringer which is the default Crowning Gift for Chaotics. This means that when/if you are crowned, whichever weapon you are currently wielding will (among other things) be unrestricted. Best of all you don't need an altar to be crowned, just high alignment & luck stats. This may be one of the rare instances in which Crowning may be "Desirable".

  Though if you plan to be crowned, you may just consider cutting out all the Sacrificing and just wish for either Frostbrand or Greyswandir while your game still has a low artifact count...