can we place "dessverre" after "komme"?
Also, in the case of infinitives. does the adverb come after the infinitive article like this example or after the main verb?
"Dessverre kan jeg ikke komme", "Jeg kan dessverre ikke komme" and "Jeg kan ikke komme, dessverre" are all accepted.
The adverb usually comes after the verb it describes.
why is "unluckily" not accepted for dessverre?
Because 'unluckily' would be more 'uheldigvis' - and, as I'm sure you can imagine, 'heldigvis' means luckily!
Also, unluckily is not a word I have ever heard in 54 years as a USAmerican. It may be a word in English but if it is, it it not commonly used.
Regrettably has exactly te same meaning
Would you still say the same for 'I cannot come unfortunately'?