Proper use of "operando"/"in operando" studies

I would expect "operando" (no "in") to be the correct form.

My Latin is a bit rusty, and this technical use of operando is new to me, but we can break down the grammar. (Magistri, please correct any dubious details in the comments!)

Operando is a gerund, i.e., a verbal noun, recognizable by its form. Gerunds often get translated into English with "-ing" gerunds, in this case "operating" or "running".

The o ending and context indicate that it is in the ablative case, which is a messy, multipurpose category for oblique functions often expressed with prepositions in English. It would be accurate to translate "operando" as "in operation" or "while running" or similar, but this form and meaning do not require the use of a preposition in Latin.

In contrast we have many phrases that use Latin nouns in the ablative to convey a similar concept (the technical means by which something is accomplished), but they often appear with the preposition "in". Why? Those phrases usually are expressing a physical (or figuratively physical) location or state in which something is accomplished (in vitro fertilization, in situ conservation, in loco parentis). For those functions and forms, Latin does use a preposition.

I hope that helps!