my experience no. but i'm unsure if you mean upgrade to silver, or REqualify for silver.

If you are talking "upgrade to silver" this is not an issue because when your April trip gets you over 30k, then they will reset you to 0 and the membership year get readjusted to 30April.

If you are talking "requalify" for Silver, different story. say after your trip you get to 35k Asiamiles... u continue that until October, reset... then start fresh. yes your "5k" will get wasted. they won't move the tier reset date to April just for this.

Then there are combination of strategy, depending on amount of wastage and your circumstances.
1) do quick run - if you are short by small margin to upgrade to silver, then u can use both J trips for requalification to next year's silver
2) remove MPC number from J trip, and do a credit afterwards. However i'm not sure if April travel can be credited in October... this works if you have immediately pending reset and don't want your miles wasted.