i suppose.  it's harmless, but i mean there is an entry for そつなく so you don't even need to conjugate anything to put these two words together

It's not listed among 348 adv+こなす collocations in NINJAL (though it does get more hits in the ngrams than any of the top NINJAL 
collocations:)
そつなくこなす	13243
きちんとこなす	6778
淡々とこなす	6074
きっちりこなす	4423
しっかりこなす	4113
なんとかこなす	2595
Still, I agree with Robin. It's just adv+verb, and it's not all that much more common than many other adv+こなす collocations.

卒なくこなす	1039
卒なく	5371
https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q11114755191

そつ indeed has no kanji, but it is being used (mistakenly) with kanji. I would like people 
to be able to look up 卒なく, etc. and be led to the right place, and be told it's an error.
I don't mind it not being here, but it may be a step too far to add it to the そつなく entry 
as "iK". It's the 事ム所 problem.

It may be common but ultimately it's just an adverb followed by a verb. I don't think it's any more worthy of inclusion than something like うまく使う.
Also, そつ has no kanji.

@@ -5,4 +5 @@
-<keb>卒なくこなす</keb>
-</k_ele>
-<k_ele>
-<keb>卒なく熟す</keb>
+<keb>そつなく熟す</keb>