What's wrong with this (real, unfortunately) fundraising sentence?
We pray that this letter finds you and your loved ones safe and well as we all face the challenge of living in a changed world due to the pandemic.
Nothing at all wrong with the sentiments it expresses. And I could nitpick it a little, noting that at 30 words, it's long -- but if other sentences around it are shorter, that's not so bad. The editorial "we" it starts with isn't a great thing, but it's not a fatal flaw.
The real problem is that it's a spaghetti bowl. Confusing awkward, stilted.
No person with an uninjured brain would say this sentence. But many people might write it ... and have no idea how terrible it is. In fact, all writers, even the very best ones, do this regularly.
But the good ones catch it and it never goes out to readers.
How the pros do this: They read their writing out loud.
Read your stuff out loud, and you'll immediately catch garbage writing.
Which will improve fundraising results. Smooth, readable, human-sounding writing is not the sole ingredient for success, but it matters.
Make the read-aloud step part of your writing process every time!