Innovation is not the same as invention. It's an extremely common misconception, but they are different things. Tweaking is far more analogous to innovating than innovating is to inventing. From the Oxford English Dictionary definition of innovate;
To bring in (something new) the first time; to introduce as new; to bring in or introduce novelties; to make changes in something established; to introduce innovations. Sometimes const. on or upon (also with indirect passive).
Whereas invent;
To come upon, find; to find out, discover; to find out or produce by mental activity; to devise, contrive; to plan, plot; to compose as a work of imagination or literary art; to treat in the way of literary or artistic composition; to devise something false or fictitious; to fabricate, feign, ‘make up’; to originate, introduce, or bring into use formally or by authority; to found, establish, institute, appoint.
and tweak;
An act of tweaking; a sharp wringing pull; a twitch, a pluck; a small modification or adjustment made to improve the efficiency of a mechanism. colloq.
To bring in (something new) the first time; to introduce as new; to bring in or introduce novelties; to make changes in something established; to introduce innovations. Sometimes const. on or upon (also with indirect passive).
Whereas invent;
To come upon, find; to find out, discover; to find out or produce by mental activity; to devise, contrive; to plan, plot; to compose as a work of imagination or literary art; to treat in the way of literary or artistic composition; to devise something false or fictitious; to fabricate, feign, ‘make up’; to originate, introduce, or bring into use formally or by authority; to found, establish, institute, appoint.
and tweak;
An act of tweaking; a sharp wringing pull; a twitch, a pluck; a small modification or adjustment made to improve the efficiency of a mechanism. colloq.