avec tous mes remerciements
with sincere gratitude in German is "in aufrichtiger Dankbarkeit"
It is "la gratitude" (fem.)
remerciements
The adjective sincere has only one spelling, sincere (frank, candid, honest, open).Words with similar spelling include censure (rebuke, condemnation) and sinecure (a position with benefits or powers, but usually no responsibilities).
French: Gratitude Spanish: Gratitud
The correct spelling is "appreciation" (gratitude).
To effectively end a presentation and leave a lasting impact on the audience, summarize key points, offer a call to action or a thought-provoking statement, and express gratitude with a sincere "thank you" for their time and attention.
reconnaissance
The way you have it spelled in your question is as good as any - it's not really a word. Sincere is a word who's comparative and superlative are : more sincere, most sincere.
To effectively express gratitude and appreciation in an acknowledgement, be specific about what you are thankful for, mention the person or people you are acknowledging, and use a sincere and heartfelt tone in your writing.
You have only one letter wrong. It is gratitude.
The correct spelling is "appreciated" (shown gratitude).