Foernekarn, have a look at the emails you receive monthly from Hilton Honors (around 10th) with subject "Your [Month] Hilton Honors Monthly Statement" - at the start on the left it will say "Current Tier Diamond" and below that "Tier Expiration Date: [Date]", which in your case I presume should read "31-Mar-2024".

Otherwise, as noted above, you can expect your stays to post correctly - with me it has always happened within 2 working days after the stay, even in border-stays as you describe. Worst-case, you can always contact support and they will correct manually if and where needed.