This is not in my tier-list of most desirable requests, but only because I assume that it is very hard to implement. So I just take it as inevitable and get used to it.
But apart from that, it must be the top one!
It will improve the quality of work in Wappler drastically.
At the moment you can’t just rename fields in tables in DB; you can’t rename or rearrange the server actions; the same for page components. Because it’s gonna mess everything up. 
P.S.: Some support for this request also here. Automatically rename table name in database query steps if changed through database manager