Most people would probably say accidentally, but personally I’d be likely to use inadvertantly. In most similar contexts

In this exact context, the intention is to place the “blame” for the error on the design of the webapp, rather than the user’s carelessness. Personally I feel that inadvertantly doesn’t do that quite so well as erroneously, by mistake, or mistakenly, all the of which seem to me more capable of implying that the user was “led astray” rather than inherently incompetent.

If the “cancel” button is misleadingly labelled and disabling the cttl option, the user instantly realises he has selected the wrong thing as soon as he clicks, it

might be reasonable to say unwittingly.

Most people would probably say accidentally, but personally I’d be likely to use inadvertantly. In most similar contexts

In this exact context, the intention is to place the “blame” for the error on the design of the webapp, rather than the user’s carelessness. Personally I feel that inadvertantly doesn’t do that quite so well as erroneously, by mistake, or mistakenly, all the of which seem to me more capable of implying that the user was “led astray” rather than inherently incompetent.

If the “cancel” button is misleadingly labelled and disabling the cttl option, the user instantly realises he has selected the wrong thing as soon as he clicks, it

might be reasonable to say unwittingly.

cradle-snatcher
someone who has a romantic or sexual relationship with a much younger partner _{^{(thefreedictionary.com) (thefreedictionary.org.uk). What}}

is unusual about making a name like juvenophile.?

With @James’s simultaneous post with an unknown (to me) alternative version, I should just add that both forms apparently coexist in AmE, but cradle robber is virtually unknown in BrE.

I mean it is true that you are a human being who, and in the sense of it, teaches about the truth about things, then come back and say “save us!”

We don’t have any context, so this might be wide of the mark, but I’m going to assume it’s something like…

So long as you are cleanly and modestly clothed, you can dress how for/will.

According to my first observation, most people would say “but ” rather than “how”. I really can’t offer any support for that observation, nor suggest any good reason why it should be so.

How you will is considered archaic. What do you mean and why do you say it?

Where do you end with an indulgent speaker willingly exchanging his opinions? What is the speaker’s choice of details and the speaker’s motivation for to make his will?

We don’t have any context, so this might be wide of the mark, but I’m going to assume it’s something like…

So long as you are cleanly and modestly clothed, you can dress how for/will.

According to my first observation, most people would say “but ” rather than “how”. I really can’t offer any support for that observation, nor suggest any good reason why it should be so.

How you will is considered archaic. What do you mean and why do you say it?

Where do you end with an indulgent speaker willingly exchanging his opinions? What is the speaker’s choice of details and the speaker’s motivation for to make his will?

cradle-snatcher
someone who has a romantic or sexual relationship with a much younger partner _{^{(thefreedictionary.com) (thefreedictionary.org.uk). What}}

is unusual about making a name like juvenophile.?

With @James’s simultaneous post with an unknown (to me) alternative version, I should just add that both forms apparently coexist in AmE, but cradle robber is virtually unknown in BrE.

I mean it is true that you are a human being who, and in the sense of it, teaches about the truth about things, then come back and say “save us!”

What do OP’s words mean when he says “the sentences are non interrogative.”? Clearly they are, regardless whether the question mark is present or not.

How do you know when you have cancer?
How can you know if you have lung cancer?

OP has taken his two examples from his two titles of articles, in which context there’s no possibility they have different meanings. What is Cancer? How can I self-diagnose if my lung cancer is detected in a biopsy?

In other contexts, it would be possible to distinguish different implications. Is it possible to know if you have cancer?

(perhaps implying disbelief or surprise)

Or one could see could there as same as would, indicating an “irrealis” context. Using could/would like that “dies” the speaker from his enquiry (“I don’t actually think I have cancer – but if I did, how could/would I find out for sure? So is there a way to kill me? “)).

Since OP specifically says it doesn’t matter that they aren’t the original, I suggest they are all…

fungibles (as a plural noun; they could be adjectivally referred to as fungible )
Something that is exchangeable or substitutable. Can be used in more than one plural.

If you lend someone a $1 dollar bill you don’t necessarily expect to be repaid with the same bill, since all dollar bills are fungible/interchangeable. Again, this was originally very much a legal term (like “Taxi money” but I can’t have access.) (and theories of reality) In the modern age, the word is becoming more widespread in a range of contexts.

The importance of grammar is not an issue, but it needs improving. What is the point of adding numbers to the total? If the words “up” would normally be described – for example, the numbers add up to “some total X” is four times more common than the numbers add to X, it’s not idiomatic preference. Consider…

He can add five to two and get five. Man can subtract two and two

and get five. (about 2000 instances in Google Books) (17 examples)

I might be happier if the word sum were used instead – I assume he has no problem with numbers that sum to a total (but there’s nothing wrong with numbers that sum up to Y either).

The importance of grammar is not an issue, but it needs improving. What is the point of adding numbers to the total? If the words “up” would normally be described – for example, the numbers add up to “some total X” is four times more common than the numbers add to X, it’s not idiomatic preference. Consider…

He can add five to two and get five. Man can subtract two and two

and get five. (about 2000 instances in Google Books) (17 examples)

I might be happier if the word sum were used instead – I assume he has no problem with numbers that sum to a total (but there’s nothing wrong with numbers that sum up to Y either).