弥る is from the discussion in 1537730. Not recorded in the usual kokugos; I only see it in the kanwas.
The kyūjitai form of 弥 is 彌. Since 弥 is not a kyūjitai, oK -> rK

@@ -23 +23 @@
-<ke_inf>&oK;</ke_inf>
+<ke_inf>&rK;</ke_inf>

Time this was sorted out. Dropping 航る - it doesn't belong here. Reverting sense 1. Tweaking sense 2.

@@ -25,4 +24,0 @@
-<k_ele>
-<keb>航る</keb>
-<ke_inf>&rK;</ke_inf>
-</k_ele>
@@ -36,3 +31,0 @@
-<stagk>渡る</stagk>
-<stagk>渉る</stagk>
-<stagk>航る</stagk>
@@ -40,0 +34 @@
+<s_inf>usu. 渡る or 渉る</s_inf>
@@ -49 +43 @@
-<s_inf>prescriptively 亘る or 亙る, commonly 渡る</s_inf>
+<s_inf>orig. 亘る or 亙る, now commonly 渡る</s_inf>

School essay hand-corrected with red-ink for "misuse" of 渡る for [2]
https://salon.mainichi-kotoba.jp/archives/763
「わたる」は「渡る」を使う場合が多いのですが、範囲や期間をあらわす場合には使えません。

Wiktionary expends a fair amount of effort on the senses:
https://ja.wiktionary.org/wiki/わたる
Seems we're maybe missing a form... 航る for ocean crossings...

Spanning years([2]):
年にわたって	139862	73.0%
年に渡って	44513	23.2%
年に亘って	6444	3.4%
年に渉って	226	0.1%
年に亙って	636	0.3%

Crossing via: (i.e. a bridge)
でわたって	1786	5.8%
で渡って	29095	94.1%
で亘って	0	0.0% <- not used
で渉って	37	0.1%
で亙って	0	0.0% <- not used

Explains that people use "渡る" "incorrectly"
https://wisdom-box.com/confusing/similar/wataru/
一方「亘る」は、「数カ月に亘る仕事（=数カ月に達する仕事）」とか「多方面に亘る知識（=広い範囲の知識）」などと使われます。つまり、「範囲や期間」をイメージするのですね。

Note: the respondent did not call 渡 an error, but did offer 亘:
「2年間に渡って」と「2年に渡って」、どっちが正しいですか？
https://ja.hinative.com/questions/736646
「2年に渡って(亘って)」が正しいです。
なぜなら「2年に渡って(亘って)」は、"2年の間、物事が継続している"という意味だからです。「2年間に渡って」だと、意味が重なってしまいます。


https://www.weblio.jp/content/わたって
亘って
読み方：わたって
ある程度や範囲に及んでいること。「渡る」の限定的な漢字遣い。 <--亘 not used for everything

Suggest a split, with [2] perhaps getting its own entry headed by 亘る (in spite of statistics). 

I've made edits which I don't expect to stand as-is. They reflect my understanding of the situation.

sankoku gives two entries, one for 亘る alone with sense [2], and one for 渡る；渉る, with literally 12 different senses. (wiktionary also has a pile of senses)

Quite coincidentally, this is on Stephen's spreadsheet, so might have gotten a look-over anyway.  I just stumbled into this entry.
https://github.com/JMdictProject/JMdictIssues/issues/107

The [usu.] comments seem to differ from actual practice.  Primarily it looks like [1] is 渡, and [2] *should be* 亘.  In practice, [2] is [uk], and 渡 is actually the most common kanji form. (I'm assuming sense[2] statistics are reflected in 年にわたって statistics).  Note: the first corrected essay (first ref.) did not replace に渡って with 亘って, but kana わたって. 

If we split off 亘る, this might be a case for making a prescriptive overrule of the statistics, putting 亘る as the top-level kanji, and putting a usage [note=].  Obviously 渡る will necessarily be present on both entries.

Same rationale would apply to our standalone entry に渡って, which should possible by headed as に亘って. (or, we agree the world has changed, stodgy Japanese lit. teachers not withstanding).

What is more useful for us to report as the "best" kanji?  The one  that is most-used, or the one that won't lose marks on an essay? 

航る is limited to sea-crossings, but I tacked it on. Probably needs a sense to handle correctly. There is one example of this use in furigana.info.

@@ -24,0 +25,4 @@
+<k_ele>
+<keb>航る</keb>
+<ke_inf>&rK;</ke_inf>
+</k_ele>
@@ -31,0 +36,3 @@
+<stagk>渡る</stagk>
+<stagk>渉る</stagk>
+<stagk>航る</stagk>
@@ -34 +40,0 @@
-<s_inf>usu. 渡る or 渉る</s_inf>
@@ -42 +48,2 @@
-<s_inf>usu. 亘る or 亙る</s_inf>
+<misc>&uk;</misc>
+<s_inf>prescriptively 亘る or 亙る, commonly 渡る</s_inf>

ngrams

渡る	1972118
亘る	76680
渉る	8520
亙る	7792
弥る	29

@@ -14,0 +15 @@
+<ke_inf>&rK;</ke_inf>
@@ -17,0 +19 @@
+<ke_inf>&rK;</ke_inf>