miq

@miq Double characters is suitable in some cases but it isn't a foolproof solution; Choosing that option requires some thought and sometimes - as with your example - some exceptions. You might want to add some out-of-order capitals, for example. 
 
Here's some insight into sequential snippets, using an example I use many times a day. We've created a huge snippet library of helpful support answers, links, code snippets, etc which we use to provide responses. I can then tailor the response, but it gives me a good starting foundation without typing til my fingers fall off.
 
For example, my response to someone who's emailed to recover their license:
 
Hi Andrew, "plS4" which expands to "No problem, please find below your Alfred 4 Powerpack license code:" [I paste their license code, which is already in my clipboard] "yen4" which expands to the explanation of where to download Alfred 4 "cV" which expands to  "Cheers, Vero"  
Aside from "Hi Andrew,", I can write the entire email in 10 typed characters, plus pasting the license code: plS4⌘vyen4cV    
 
Each snippet takes care of including the necessary trailing new lines to ensure I'm at the right place for the next sequential snippet I'm pasting.  While my snippets are short, they won't be accidentally triggered as they don't use a normal combination of letters I'm likely to type in everyday phrases.
 
Andrew describes your scenario as a corner case as it's the first time this issue has been raised, throughout the years since we released this feature. We are always listening to the community, and read every thread and email. If many users were encountering this issue, we would certainly consider providing solutions. However, for the time being, this would just complicate the text expansion settings further.
 
Cheers,
Vero

Why does it do that? That sounds sub-optimal. I mean, what's the purpose of being able to turn off mid-string expansion if you still always have to use keywords that never occur anywhere in a word (and not just at the start)?
 
In @miq's case, there's no question that the cursor is in the middle of a word. It makes no difference to the text or the user whether Alfred inserted the first half of the word or they did. It seems to me, it would be better if it didn't matter to Alfred, either.
 

Meanwhile I have made up an English example that is not so realistic but hopefully is easier to follow. I post it here, even if the problem is probably already clear thanks to @deanishe (thanks!).
 
Say we have two snippets: 
- keyword 'hha' for snippet "hand|"
- keyword 'icr' for snippet "craftsman|".
 
1. We want to type the word "handicap":
Typing snippet 'hha' + rest of the word 'icap', we get: "handicap". ✅
 
But:
2. We want to type "handicraft":
Typing snippet 'hha' + rest of the word 'icraft', as soon as we type 'hhaicr', Alfred recognizes 'hha' and 'icr' and expands both to "handicraftsman" even though 'icr' is mid-string.
 
As I said, this example might be a little constructed. In German though, we hava lots of long compound words…

They're typing "Oor" which expands to "Organisation|", then they start typing "ssystem" to complete the word "Organisationssystem", whereby Alfred recognises the snippet keyword "ssy" and expands it (to "systemtheoretisch") even though "Expand snippets mid-string" is turned off.
 
Alfred appears not to notice if an expansion has left the cursor mid-string, so if you immediately type another snippet keyword, it will expand it even though the cursor is mid-string and mid-string expansion is turned off.