Combination franking with 2 sen, postcard from Yokohama, Japan to Sailor on Austrian Navy ship, SMS Radetzky

Here is one I purchased that came in the mail a couple of weeks ago and since then I have been doing my research with a little help from others on another stamp forum I belong to. The sender is Czech and the short message is in Czech.

Two knowledgeable and reliable sources tell me the postcard was sent to a sailor on the Austrian navy ship, SMS Radetzky. Apparently he was no longer on that ship when it was received and was forwarded to the SMS Kaiser Karl VI at the Pola naval base.
"The addressee is named as "imperial and royal [k.k.]] sailor [Matrose] on HMS Radetzky" (changed to HMS Emperor [K.] Karl IV)".

The short text on the reverse is written in Czech. The first - legible - words read: "Why don't you write about...". (I cannot identify the rest of the handwriting)."

Austria-Hungary had a navy from the late 1700s until they surrendered in 1918 when the empire was collapsing during WWI. Both of the ships above would be scrapped by 1920.
The combination franking including a 2 sen, 1 1/2 sen and 1/2 sen with partial imprint have nice Yokohama cancels dated June 6, 1917.

Something else that makes this cover appealing to me is the little bit of dragonfly wing that shows up under 1 1/2 sen stamp. I may not have mentioned here but I have another topical collection other than Expo '70 and that is dragonflies on stamps. If I remember correctly these postcards with the dragonfly imprint have a specific name that I have seen mentioned at some point in the past.

I welcome any corrections or additional input regarding what I have said above or in reference to this cover.